Active compression decompression cardiopulmonary resuscitation chest compression feedback

ABSTRACT

Systems and methods related to the field of cardiac resuscitation, and in particular to devices for assisting rescuers in performing cardio-pulmonary resuscitation (CPR) are described herein. The system includes an applicator device configured to provide ACD CPR treatment to a patient&#39;s chest according to a plurality of phases at least one sensor configured to be coupled to the patient&#39;s chest and to measure at least one parameter related to the ACD CPR treatment and information for determining whether at least one transition point of the ACD CPR treatment has been reached; and one or more processors configured to provide a feedback signal based on a parameter for administering ACD CPR treatment to the patient&#39;s chest according to a desired treatment protocol.

RELATED APPLICATION

This application is a continuation application of U.S. Application Ser.No. 17/344,343, filed on Jun. 10, 2021, which is a continuationapplication of U.S. application Ser. No. 15/720,837, filed on Sep. 29,2017, which claims priority to U.S. Provisional Patent Application No.62/402,688 filed on Sep. 30, 2016, the entire content of which is herebyexpressly incorporated by reference herein.

TECHNICAL FIELD

This document relates to cardiac resuscitation systems, and inparticular to systems for assisting rescuers in performing andoptimizing chest compressions performed in association withcardio-pulmonary resuscitation (CPR).

BACKGROUND

Acute care is delivered to patients in emergency situations in thepre-hospital and hospital settings for patients experiencing a varietyof acute medical conditions involving the timely diagnosis and treatmentof disease states that, left alone, will likely degenerate into alife-threatening condition and, potentially, death within a period of 72hours or less. Stroke, dyspnea (difficulty breathing), traumatic arrest,myocardial infarction and cardiac arrest are a few examples of diseasestates for which acute care is delivered to patients in an emergencysetting. Acute care comprises different treatment and/or diagnosis,depending upon the disease state. Cardiac arrest is one example thathighlights critical interactions between the heart and the brain, and itremains a leading cause of death. Other examples include shock,traumatic brain injury, dehydration, kidney failure, congestive heartfailure, wound healing, diabetes, stroke, respiratory failure, andorthostatic hypotension.

Despite advances in the field of circulatory enhancement, the need forimproved approaches for treating patients with impaired circulationremains an important medical challenge. One example of acute care iscardio-pulmonary resuscitation (CPR), which is a process by which one ormore acute care providers may attempt to resuscitate a patient who mayhave suffered an adverse cardiac event by taking one or more actions,for example, providing chest compressions and ventilation to thepatient. Evidence indicates that promptly re-establishing systemic bloodflow and thereby maintaining threshold levels of coronary and cerebralperfusion can increase the success of the CPR treatment.

Chest compressions are an important element of CPR during the first fiveto eight minutes after CPR efforts begin, because chest compressionshelp maintain circulation through the body, heart, and brain, which arethe organs that can sustain substantial damage from an adverse cardiacevent. Traditional chest compressions include two phases: one, which isreferred to as the “active compression phase” where the chest iscompressed by the direct application of external pressure and anotherone, which is referred to as the “relaxation phase” and occurs whenpressure is withdrawn and the natural elasticity of the patient's chestwall causes expansion. The chest expansion of the relaxation phaseserves to partially refill the cardiac chambers with blood. Inconventional CPR, the air necessary for blood oxygenation is providedthrough periodic ventilation of the patient. Generally, American HeartAssociation CPR Guidelines define protocols, by which a rescuer is toapply the chest compressions in coordination with ventilations. Forexample, 2015 AHA Guidelines specify a ratio of 30:2 for compressions toventilations (e.g., thirty compressions for every two breaths) andcompressions are to be performed at a rate of between 100 and 120 perminute.

SUMMARY

This document describes systems and techniques that can be used to helpmanage a cardiopulmonary resuscitation (CPR) treatment to a patient inneed of emergency assistance. In one implementation, a system includes:an applicator device configured to provide active compressiondecompression (ACD) therapy to a patient's chest, at least one sensorconfigured to be coupled to the patient's chest and to measure at leastone parameter related to the ACD CPR treatment, and one or moreprocessors configured to perform a plurality of operations. Theoperations include processing the at least one parameter related to theACD CPR treatment, determining the phase of the ACD CPR treatment andwhether at least one transition point in the ACD CPR treatment has beenreached, and generating a feedback signal based on the determination,wherein the feedback signal is selected according to a predeterminedtreatment protocol.

In another implementation, a system includes: an applicator deviceconfigured to provide the ACD CPR treatment to a patient's chestaccording to a plurality of phases, the phases comprising at least anelevated compression phase, a non-elevated compression phase, anelevated decompression phase, and a non-elevated decompression phase, atleast one sensor configured to be coupled to the patient's chest and tomeasure at least one parameter related to the ACD CPR treatment, and oneor more processors configured to perform a plurality of operations. Theoperations include processing the at least one parameter related to theACD CPR treatment, determining the phase of the ACD CPR treatment basedon the information for determining whether at least one transition pointhas been reached, the at least one transition point including atransition between an elevated position above a neutral point and anon-elevated position below the neutral point, and providing a feedbacksignal based on the at least one parameter for administering ACD CPRtreatment to the patient's chest according to a desired treatmentprotocol.

In some aspects, the at least one sensor includes at least one of amotion sensor and a force sensor. The motion sensor can measure the atleast one parameter related to the ACD CPR treatment. The force sensorcan measure the at least one parameter related to the ACD CPR treatment.The motion sensor can measure the information for determining whether atleast one transition point of the ACD CPR treatment has been reached.The motion sensor can include one or more accelerometers configured todetect an acceleration signal associated with the displacement of the atleast the portion of the patient's chest. A first accelerometer can beconfigured to detect an acceleration signal associated with displacementof a first portion of the patient's chest and a second accelerometer canbe configured to detect an acceleration signal associated withdisplacement of a second portion of the patient's chest.

In other aspects, the information for determining whether the at leastone transition point has been reached can include at least one ofdisplacement information and force information. The at least onetransition point can include a transition point between an elevatedposition above a neutral point and a non-elevated position below theneutral point. The transition point can be between a non-elevateddecompression phase and an elevated decompression phase. The feedbacksignal can include providing a prompt to maintain a desired releasevelocity during decompression upstroke for providing a negativeintrathoracic pressure according to the desired treatment protocol.

In yet another aspect, the prompt to maintain the desired releasevelocity can include at least one of an audio prompt, a verbal prompt, anon-verbal prompt, a visual prompt, a graphical prompt and a hapticprompt. The prompt to maintain the desired release velocity can includea signal for operating an automated compressor. The feedback signal caninclude providing a prompt to limit a force applied to the patient'schest during decompression upstroke for reducing risk of injuryaccording to the desired treatment protocol. The prompt to limit a forceapplied to the patient's chest during decompression upstroke can includeat least one of an audio prompt, a verbal prompt, a non-verbal prompt, avisual prompt, a graphical prompt and a haptic prompt. The prompt tolimit a force applied to the patient's chest during decompressionupstroke can include a signal for operating an automated compressor.

In yet another aspect, the transition point can be between an elevatedcompression phase and a non-elevated compression phase. The at least onetransition point can include a transition point between an elevateddecompression phase and an elevated compression phase. The transitionpoint can be between an elevated decompression phase and a hold timeabove a neutral point. The transition point can be between a hold timeabove the neutral point and an elevated compression phase. The hold timecan be between about 50-200 milliseconds. The hold time can besufficient to promote net blood flow to the heart of the patient.

In yet another aspect, the feedback signal can include providing aprompt to maintain at least one of a compression depth and a compressionrate according to the desired treatment protocol. The prompt to maintainat least one of a compression depth and a compression rate can includeat least one of an audio prompt, a verbal prompt, a non-verbal prompt, avisual prompt, a graphical prompt and a haptic prompt. The prompt tomaintain at least one of a compression depth and a compression rate caninclude a signal for operating an automated compressor. The feedbacksignal can include providing information regarding at least one of adisplacement above the neutral point and a depth of compression belowthe neutral point.

In yet another aspect, the at least one transition point can include atransition point between a non-elevated compression phase and anon-elevated decompression phase. The transition point can be between anon-elevated compression phase and a hold time below the neutral point.The transition point can be between hold time below the neutral pointand a non-elevated decompression phase. The hold time can be betweenabout 50-200 milliseconds. The hold time can be sufficient to promotenet blood flow to the head of the patient. The feedback signal caninclude providing a prompt to ventilate during decompression upstroke.The prompt to ventilate can include at least one of an audio prompt, averbal prompt, a non-verbal prompt, a visual prompt, a graphical promptand a haptic prompt. The prompt to ventilate can include a signal foroperating an automated ventilator.

In yet another aspect, the feedback signal can include providing aprompt to maintain a sufficient release velocity during decompressionupstroke for providing a negative intrathoracic pressure according tothe desired treatment protocol. The at least one parameter related tothe ACD CPR treatment can include at least one of displacement,velocity, acceleration, time, work, power, pressure, direction andorientation. The feedback signal can include providing a prompt tomaintain the applicator device according to a desired orientation duringapplication of the ACD CPR treatment.

In yet another aspect, the system can include a user interfaceconfigured to assist the rescuer interacting with the applicator devicefor providing ACD CPR treatment to the patient's chest. The userinterface can be configured for displaying information representingeffectiveness of CPR chest compressions. The user interface can beconfigured for displaying an indication of the phase of the ACD CPRtreatment. The user interface can be configured to be displayed on adevice external to the system (e.g., smartphone, smartwatch, tabletdevice, monitor, diagnostic device, or defibrillator). The applicatordevice can include one or more accelerometers configured to detect anacceleration signal associated with displacement of the applicatordevice. The system can include an adhesive pad configured to be adheredto at least a portion of a patient's chest.

In another implementation, a system for managing CPR treatment to apatient in need of emergency assistance by a rescuer can include: achest decompression monitor configured to be adhered to and to detect adisplacement of at least a portion of a patient's chest, an applicatordevice that can be configured to be releasable coupled to the chestdecompression monitor and can be configured to generate a decompressionforce to be applied to the at least the portion of the patient's chest,and one or more processors configured to process the displacement and toprovide a feedback associated with the decompression force.

In one aspect, the applicator device can include a motor for driving theapplicator device to generate the decompression force. The system caninclude an automated controller for operating the motor, the automatedcontroller being programmed to control the decompression force inresponse to the feedback provided by the one or more processors. Thesystem can include a user interface configured to assist the rescuerinteracting with the applicator device by providing instructions togenerate the decompression force. The user interface being configuredfor displaying information representing effectiveness of CPR chestcompressions. The user interface can be configured for displaying acompression non-elevated depth. The user interface can be configured fordisplaying a decompression elevated height. The user interface can beconfigured for displaying a trend graph representing chest remodeling.The user interface can be configured to be displayed on a deviceexternal to the system. The device external to the system can include atleast one of a smartphone, a smartwatch, or a tablet device.

In other aspects, the chest decompression monitor can include one ormore accelerometers configured to detect an acceleration signalassociated with the displacement of the at least the portion of thepatient's chest. The one or more processors are configured to processthe acceleration signal to determine one or more of a velocity, anupstroke and a release time. A first accelerometer can be configured todetect the acceleration signal associated with the displacement of aleft portion of the patient's chest and a second accelerometer can beconfigured to detect the acceleration signal associated with thedisplacement of a right portion of the patient's chest. The applicatordevice can include one or more accelerometers configured to detect anacceleration signal associated with the displacement of the applicatordevice. The system can include a sensor configured to measure atrans-thoracic impedance of the patient. The system can include a sensorconfigured to measure a tracheal pressure of the patient.

In another implementation, a system for applying guided activecompression-decompression cardiopulmonary resuscitation to a patient inneed thereof can include: an adhesive pad configured to be adhered to atleast a portion of a patient's chest, an applicator device coupled tothe adhesive pad and can be configured to generate a force to be appliedto the at least the portion of the patient's chest, a sensor configuredto monitor a signal of the at least the portion of the patient's chestin response to the force applied by the applicator device, and one ormore processors configured to process the signal and to identify a phaseof the ACD cardiopulmonary resuscitation.

In one aspect, the phase can be one of a non-elevated compression, anon-elevated decompression, an elevated decompression, and an elevatedcompression phases.

The one or more processors are configured to perform a calibration basedon the identification of the phase. The one or more processors areconfigured to generate feedback based on the motion signal and thephase. The feedback can include at least one of a depth, a force orpressure amplitude, a force direction, a velocity, a compliance, apower, a release time, a displacement limit and a trans-thoracicimpedance of the patient.

In another implementation, a system for applying guided ACDcardiopulmonary resuscitation to a patient in need thereof, can include:an adhesive pad configured to be adhered to at least a portion of apatient's chest, an applicator device coupled to the adhesive pad andcan be configured to generate a decompression force to be applied to theat least the portion of the patient's chest, a sensor configured tomonitor a fluid displacement in the patient in response to thedecompression force applied by the applicator device, and one or moreprocessors configured to provide a feedback based on the fluiddisplacement.

In some aspects, the system can include a valve to control the fluiddisplacement in response to the feedback. The sensor can be attached toa ventilation bag and can be configured to monitor air flow through theventilation bag. The sensor can be configured to monitor a venous returnin the patient. The sensor can be configured to monitor a trachealpressure of the patient.

In other aspects, the system can include one or more motion sensors. Theone or more motion sensors are included in the chest decompressionmonitor and are configured to detect an acceleration signal associatedwith the displacement of the at least the portion of the patient'schest. A first motion sensor can be configured to detect theacceleration signal associated with the displacement of a left portionof the patient's chest and a second accelerometer can be configured todetect the acceleration signal associated with the displacement of aright portion of the patient's chest. The one or more motion sensors areincluded in the applicator device and are configured to detect anacceleration signal associated with the displacement of the applicatordevice.

Other features and advantages will be apparent from the description,from the drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows an example graph including temporal variation of an exampleof a signal indicative of ACD CPR chest compression treatment.

FIG. 2 shows another example graph including temporal variation of anexample of a signal indicative of ACD CPR chest compression treatment.

FIG. 3 shows an overhead view of rescuers providing resuscitativetreatment to a patient using a CPR chest compression assistance systemin accordance with an embodiment.

FIGS. 4A and 4B show frontal and perspective views of the CPR chestcompression assistance system in accordance with an embodiment.

FIGS. 4C and 4D show perspective views the CPR chest compressionassistance system according to compression and active decompressionprotocols.

FIGS. 5A and 5B show top and cross-sectional views of an example ACDdevice in accordance with an embodiment.

FIGS. 5C, 5D, and 5E show bottom views of an example ACD device inaccordance with illustrative embodiments.

FIG. 6 shows a portable defibrillator and ancillary components arrangedto provide feedback and instruction to rescuers in accordance withcertain embodiments.

FIG. 7 shows example chest compression inputs and mechanisms foranalyzing the inputs to determine whether a different person can providechest compressions.

FIG. 8 illustrates a defibrillator showing some types of informationthat can be displayed to a rescuer.

FIGS. 9A-9C show screenshots of a defibrillator display that providesfeedback concerning chest compressions performed on a patient.

FIGS. 10A and 10B show screenshots providing feedback for CPR.

FIGS. 11A and 11B show screenshots of a display providing ACD CPRfeedback.

FIG. 12 shows an example of a flowchart of a process for providingfeedback to a user during the performance of ACD CPR chest compressiontreatment.

FIG. 13 shows a general computer system that can provide interactivitywith a user of a medical device, such as feedback to a user in theperformance of CPR chest compression treatment.

DETAILED DESCRIPTION

Implementations of the present disclosure are generally directed tosystems for managing a cardiopulmonary resuscitation (CPR) treatment toa patient in need of emergency assistance, such as a patient sufferingof cardiac arrest. In particular, implementations of the presentdisclosure are generally directed to systems for assisting a rescuer toperform active compression decompression (ACD) CPR chest compressions.ACD CPR differs from standard CPR chest compressions in that thepatient's chest is actively pressed and lifted in an alternating manner.An exemplary device to assist in the performance of ACD CPR is theRESQPUMP® (provided by ZOLL Medical). Such devices have the ability tocouple to the patient's chest to facilitate lifting of the chest duringthe decompression phase. By actively lifting the chest, the negativeintrathoracic pressure is increased causing more venous blood to flow tothe heart and lungs during the decompression phase. Thus, in addition tocompression of the chest to improve blood flow from the heart toperipheral tissues of the body, decompression of the chest offeredthrough ACD reduces intrathoracic pressure, resulting in enhanced venousreturn of blood from peripheral tissues back to the heart and refillingof the cardiac chambers. ACD treatment involves a number of differentphases that each have respective effects on the body. Referring to FIG.1 , standard CPR (S-CPR) chest compressions do not have the ability toactively decompress the chest during the decompression phase, andtherefore, for S-CPR, the expansion of the chest is based solely on thenatural elasticity of the patient's chest wall. With S-CPR, upon releaseof compression forces on the sternum, there is no external decompressiveforce on the sternum exerted by the rescuer, and so is only composed ofthe non-elevated compression and non-elevated decompression phases. Onthe other hand, ACD CPR actively re-expands (decompresses) the chest,and therefore may be composed of both elevated compression anddecompression phases and non-elevated compression and decompressionphases.

The example graph 1 includes a temporal (X) axis 100 a and adisplacement (Y) axis 100 b. The neutral position 116 is thedisplacement at which zero static compression or decompression force isexerted by the rescuer on to the patient during compressions. Theexample graph 100 includes a plurality of neutral points 116 and otherphase transition points 110 a, 110 b, 110 c, and 110 d. Accordingly, thefeedback provided to a user or system providing ACD treatment to apatient may vary depending on the particular phase of ACD such that thefeedback can be a phase-specific feedback. The phase-specific feedbacksignal can be selected according to a predetermined treatment protocol.For performing an ACD CPR chest compression treatment, a rescuer canattach the system for managing ACD CPR chest compression treatment to apatient's chest and apply force on a handle of the system duringmultiple phases of ACD CPR chest compression treatment.

It is desirable for the phases of ACD CPR chest compression treatment tobe analyzed and distinguished from one another so that phase-specificfeedback can be provided and the rescuer can optimize delivery of thecompression and decompression for maximal therapeutic benefit. Referringto FIGS. 1 and 2 , these phases may include at least one of an elevatedcompression, non-elevated compression, non-elevated decompression, andelevated decompression phases. If the phases can be identified, feedbackcan be provided to a rescuer that directs the rescuer to perform chestcompressions that are likely to be more effective at resuscitating thepatient and less likely to lead to injury. For example, feedback couldbe provided directing the rescuer to maintain release velocity duringupstroke and optionally hold (pause) above a neutral point of chestcompression, which may have a tendency to enhance blood flow back intothe heart. As another example, feedback could be provided directing therescuer to hold (pause) below the neutral point of chest compression,which may have a tendency to enhance blood flow to the head, resultingin a greater likelihood of neurologically intact survival.

FIG. 1 illustrates an example graph 100 including temporal variation ofan example of a signal indicative of ACD CPR chest compressiontreatment. In some implementations, the example graph 100 corresponds toa sternal displacement as determined from a motion sensor such as anaccelerometer as described below with reference to FIGS. 3 and 4 , suchas a signal depicting the force applied to the chest of a patient or thedisplacement of the patient's chest during ACD CPR chest compressiontreatment. In some implementations, data corresponding to the graph 100would be calculated by a computer system, e.g., one or more computerprocessors of a defibrillator (e.g., the defibrillator 312 shown in FIG.3 ) or an ACD device (e.g., the ACD device 408 shown in FIG. 4 ) oranother kind of computer system (e.g., the computer system 310 shown inFIG. 3 ).

The neutral position location 116 or other phase transition points maybe determined using techniques for instance as described in “ChestCompliance Directed Chest Compressions”, filed on Sep. 16, 2016 as U.S.patent application Ser. No. 15/267,255 and published as U.S. PatentPublication No. 2017-0079876, and is incorporated by reference herein inits entirety. In some examples, the neutral position may be determinedbased on data such as an estimated depth of chest compression and anestimate of chest compliance. For example, when a victim's chest is at aneutral position of chest compression (generally corresponding to thenatural resting position of the chest), chest compliance tends to be atits highest point. This may be determined, e.g., using a point ofintersection of a hysteresis compliance curve, because the point ofintersection tends to correspond to a neutral position of chestcompression.

The neutral position 116 may be identified as the position at which zeroforce or pressure is exerted by the rescuer during ACD compressions andthe spatial variation transitions from a negative value to a positivevalue or from a positive value to a negative value. Because of so-calledchest remodeling that occurs during chest compressions, this zero-forceneutral position 116 may change over the course of resuscitationefforts, as the anterior/posterior diameter of the patient will decreaseafter multiple compression cycles. Alternatively, the neutral positionlocation 116 may be simply the initial position of the sternum prior toinitiation of chest compressions.

The example graph 100 illustrates the phases of the ACD CPR chestcompression treatment: a non-elevated compression phase 102, anon-elevated decompression phase 104, an elevated decompression phase106, and an elevated compression phase 108. The non-elevated compressionphase 102 corresponds to the time interval during which a rescuer isactively compressing the patient's chest as a downstroke from a neutrallevel to a particular compression depth. The non-elevated decompressionphase 104 corresponds to the time interval during which a rescuer isdecompressing the patient's chest as an upstroke from a particularcompression depth to a neutral level. The non-elevated decompressionphase 104 may or may not be active in nature. That is, the acute careprovider may actively pull up on the patient's chest at an upwardvelocity faster than the natural velocity of chest wall recoil,enhancing the overall effects of chest wall recoil (e.g., increasingnegative intrathoracic pressure). Or, the acute care provider may pullup or reduce the applied force in a manner that allows the patient'schest to undergo natural recoil. Here, the release velocity may be thesame as or slower than the natural recoil velocity of the chest.

The elevated decompression phase 106 corresponds to the time intervalduring which a rescuer is actively decompressing the patient's chest.This active decompression may occur during either the non-elevated orelevated decompression phases 104, 106. Active decompression involvespulling upward of the chest wall to further enhance negativeintrathoracic pressure. The elevated compression phase 108 correspondsto the time interval during which a rescuer is compressing the patient'schest from a particular decompression amplitude to the neutral level.The elevated compression phase 108 may or may not be active in nature.For instance, the acute care provider may let go or otherwise releasethe patient's chest to allow the chest to naturally rebound. Or, theacute care provider may actively push down on the patient's chest at adownward force that causes the chest to return back to its natural statefaster than would otherwise be the case if the chest was simply let go.Transition points 110 a, 110 b, 110 c, and 110 d define the pointcorresponding to the end of a phase and the beginning of another phaseof the ACD chest compression treatment.

In some implementations, the transition between elevated andnon-elevated phases can correspond to the neutral points 116 of thepatient's chest wall (e.g., the level at which the chest wall would beif ACD CPR chest compression treatment would not be applied, which canbe measured before the initiation of the ACD CPR chest compressiontreatment). Transition points 110 a, 110 b, 110 c, and 110 d can bebetween compression and decompression phases, or between eithercompression or decompression and plateau phases.

In some implementations, the transition points 110 a, 110 b, 110 c, and110 d can be detected by a transition point detector based on athreshold. Such a transition point detector may be part of the system,taking one or more inputs from the sensor(s) associated with the ACDdevice, and determining from the input(s) whether a transition hasoccurred between phases of ACD CPR treatment. The particular type offeedback provided to the rescuer may be selected and suitably presentedto the rescuer, based on the detection of a transition from one phase toanother. For example, each ACD CPR treatment is associated with acompression range between a maximum compression and a maximumdecompression. The maximum compression and decompression values can bepreset values stored in a database. The maximum compression value can beassociated with a transition point 110 a and/or 110 b. The maximumdecompression can be associated with a transition point 110 c and/or 110d. The transition points can be associated with maximum compression ordecompression based on a comparison of chest displacement at incrementsof time (e.g., every millisecond) represented as variation alongdisplacement axis 100 b relative to the time axis 100 a.

An ACD CPR chest compression treatment template can define thespatio-temporal path of the compression treatment, such as example graph100, from the neutral point 116 to the first transition point 110 awithout exceeding a first threshold (e.g., a desired maximum compressionvalue) and from the neutral point 116 to the following transition point110 c without exceeding a second threshold (e.g., a desired maximumdecompression value). In some implementations, the scalar value of thefirst threshold can be different than the scalar value of the secondthreshold. Further, each of the first threshold and the second thresholdcan be selected based on one or more physiological characteristics(e.g., chest compliance).

In some implementations, the threshold values are preset values, whichmay be selected based on chest compliance. For example, the thresholdvalues can depend on one or more physical characteristics (e.g., size,weight, and other physical measurements/records) of a patient. Thethreshold values can be calculated prior to the ACD CPR chestcompression treatment or they can be retrieved from a stored medicalfile based on patient's characteristics. In some implementations, thethreshold values can be used to control the transition between multiplephases of the ACD CPR chest compression treatment, such that limitingthe decompression force above neutral point 116 can lessen the risk ofrib fracture.

For example, a threshold detector can monitor the spatio-temporal pathof the compression treatment, such as example graph 100, and in responseto detecting a transition point 110 a of a non-elevated compression itcan trigger the initiation of the following phase, such as anon-elevated plateau phase 112 or a non-elevated decompression phase104. The monitoring of the spatio-temporal path can be based, forinstance, on data provided by a motion sensor such as an accelerometer,positioned at the location of the chest wall at which ACD therapy isdelivered. In such a case, the acceleration data may be single- anddouble-integrated to determine the displacement as well as the change indisplacement of the chest wall. Accordingly, during the non-elevatedcompression phase 102, a transition point 110 a may be detected when thechange in displacement of the chest wall during downstroke is reduced bya threshold amount (e.g., change in displacement reduced to less than20%, less than 10%, etc.). The transition point 110 b may be furtherdetermined when the change in displacement shifts in an oppositedirection so as to detect the decompression upstroke. For example, thetransition point 110 b may be detected when the change in displacementof the chest wall is increased by a threshold amount (e.g., change indisplacement increased by more than 50%, more than 60%, more than 70%,more than 80%, etc.). Accordingly, as discussed herein, where the typeof feedback selected and presented during non-elevated compression 102may be related to chest compression depth/rate, upon transitioning tonon-elevated decompression 104, the type of feedback selected andpresented may be related to release velocity.

In some implementations, the example graph 100 includes one or moreplateau phases, such as a non-elevated plateau phase 112 and an elevatedplateau phase 114. In some examples, the detector may determine that aplateau phase has been reached if the displacement of the chest wallremains substantially constant and/or the change in displacement isminimal. The plateau phases 112 and 114 can correspond to a hold time.The hold time can be included in the ACD CPR chest compressiontreatment, for example, to help improve vascularization and oxygenation.For example, holding a non-elevated plateau phase 112 for a suitableperiod of time can be sufficient to promote net blood flow to the headof the patient by overcoming inertia that may normally be present withinthe vasculature. For example, holding an elevated plateau phase 114 fora suitable period of time can be sufficient to promote net blood flow tothe heart of the patient (e.g., to enhance venous return and refillingof the cardiac chambers). The hold time corresponding to thenon-elevated plateau phase 112 and/or the elevated plateau phase 114 canbe between about 10-1000 milliseconds, between about 10-500milliseconds, between about 10-200 milliseconds, between about 50-200milliseconds, between about 200-500 milliseconds, or a period of timefalling within another suitable range.

During elevated compression and non-elevated compression, a rescuer canpress downwardly on a handle of the system with sufficient force tocompress the patient's chest from a level above a neutral point of thechest wall to a level below the neutral point. This action inducesarterial blood circulation by ejecting blood from cardiac chamberstoward peripheral tissues. As discussed herein, the type of feedbackprovided during non-elevated compression may include chest compressiondepth and chest compression rate.

On the other hand, during non-elevated decompression and elevateddecompression phases of ACD CPR, the rescuer can pull upwardly on thehandle of the system to actively expand the patient's chest. Activelyshifting the position of the chest wall from that which would beachieved by the natural recoil of the chest wall enhances refill ofblood back into the cardiac chambers and, in some cases, may furtherassist in brining air into the patient's lungs in a more efficientmanner. As discussed herein, the type of feedback provided duringnon-elevated decompression and elevated decompression may includerelease velocity. The feedback provided during elevated decompressionmay further include force along with release velocity. This is becauseoverly excessive decompression force on the chest of the patient,particularly during the elevated decompression phase may lead to injury.Accordingly, the ACD device may include one or more force sensors, 532,533, that provide an indication to the system of how much force isapplied by the rescuer. Once a threshold level of force is reached, thesystem may inform the rescuer that the decompression force is too high.During the decompression phase (non-elevated and elevated), while it maybe desirable to reach a sufficient release velocity to beneficiallygenerate a reduced level of intrathoracic pressure, the force applied tothe chest in efforts to achieve such release velocities should not be sovigorous such that excessive levels that would result in harm to thepatient are achieved.

In some versions of the system, feedback may be provided on measurementsof some feature of the non-elevated compression phase 102 and theelevated decompression phase 106. As noted, in some cases, the feedbackfeature for the non-elevated compression phase may be the compressiondepth, and the feature of the elevated decompression phase 106 may besome force or pressure measurement occurring during the elevateddecompression (ED) phase 106. The force or pressure measurement duringthe ED phase may be an average, peak, median, RMS, or other mathematicalcharacterization of the force or pressure, and compared to a set ofdesired levels to result in favorable patient outcomes. For example, asdiscussed above, the system may provide feedback such that theforce/pressure during the ED phase is not overly excessive. Accordingly,if a certain threshold level of force is reached during the ED phase,the system may alert the user that excessive levels of force have beenreached. Such threshold levels may be set according to patientcharacteristics, or default values may be provided. In some embodiments,the maximum threshold force values may be between approximately 10-30kg, between approximately 10-15 kg.

Each of the phases of the ACD chest compression cycle can be monitoredfor one or more compression cycle and feedback provided so that therescuer can optimize delivery of the compression and decompression formaximal therapeutic benefit. For example, the compression magnitude canbe in a range from about 3.5 cm to about 5 cm for the non-elevatedcompression phase 102 and the compression rate can be in a range fromabout 60 compressions to about 150 compressions per minute. In certainembodiments, the recommended compression rate for ACD therapy may beapproximately 80 compressions per minute.

FIG. 2 illustrates another example graph 200 including temporalvariation of an example of a signal indicative of ACD CPR chestcompression treatment. As compared to FIG. 1 , the example graph 200FIG. 2 illustrates longer periods of the plateau phases and reduceddecompression phases 224 and 226 and compression phases 228 and 222. Theexample graph 200 could be performed through real-time feedbackcontrolled treatment. The example graph 200 includes a temporal axis 200a and a displacement axis 200 b, the intersection of which marks theneutral point 236 of the patient's chest. The transition points 230a-230 j define the transitions between elevated and non-elevated phasesof the ACD CPR chest compression treatment. In some implementations,some transition points (e.g., transition point 230 c) can correspond tothe neutral point 236 of the patient's chest wall (e.g., the level atwhich the chest wall would be if ACD CPR chest compression treatmentwould not be applied, which can be measured before the initiation of theACD CPR chest compression treatment). Some transition points (e.g.,transition points 230 a, 230 b, 230 c, 230 d, 230 e, 230 f, 230 g, 230h) can be above or below the neutral point 236 a, 236 b, 236 c, 236 d,236 e of the patient's chest wall.

In some implementations, the example graph 200 includes one or moreplateau phases, such as a non-elevated plateau phase 232 and an elevatedplateau phase 234. The plateau phases can correspond to a time ofapproximately constant compression and decompression force,respectively. The approximately constant force time can be included inthe ACD CPR chest compression treatment to improve vascularization andoxygenation. The transition from a non-elevated compression or elevateddecompression to a plateau phase can be a smooth transition, such thatthe variation of the compression or decompression force and/ordisplacement relative to time is gradually decreasing until the force ordisplacement remains approximately constant over a preset time. Thepreset time can be selected based on one or more physiologicalparameters. The preset time of a non-elevated plateau phase 232 can besufficient to promote net blood flow to the head of the patient. Thepreset time of an elevated plateau phase 234 can be sufficient topromote net blood flow to the heart of the patient. The preset timecorresponding to the non-elevated plateau phase 232 and/or the elevatedplateau phase 234 can be between about 50-200 milliseconds.

In some implementations, the rescuer is guided into performing a smoothtransition from an active compression or decompression to a plateauphase (e.g., corresponding to an exponential variation in the appliedforce until it reaches a particular compression threshold 238 and/ordepression threshold 240). The compression threshold 238 and/ordecompression threshold 240 can be selected based on physiologicalcharacteristics of the patient and/or ACD CPR chest compressionrequirements.

For example, the feedback provided to limit the decompression forceabove the neutral point below the depression threshold 240 can beconfigured to decrease the risk of rib fracture in a patient with aparticular body structure. In some embodiments, the elevateddecompression phase 226 and the elevated plateau phase 234 can besynchronized with patient's ventilation. Alternatively, the patient'sventilation can be synchronized to occur during both the non-elevateddecompression and elevated decompression phases (i.e. substantially thewhole of the decompression phase) as ventilation will be more efficientand safer when the ventilation occurs when the intrathoracic pressure isnegative such as during the decompression phase. In some versions, thesynchronization may be accomplished based on feedback provided to therescuer such as a prompt that indicates when a ventilation is to startand stop. That is, when a transition point is detected such that thesystem determines that non-elevated decompression is beginning, thesystem may provide a prompt to a user and/or machine to initiate apositive pressure ventilation breath. For example, the synchronizationmay be accomplished based on an output to a mechanical ventilation unitthat indicates which of the phases an inspiratory ventilation cycle canoccur.

FIG. 3 shows an example of a system 300 for responding to an emergencymedical condition of a patient 302 by providing CPR chest compression.FIG. 3 illustrates an overhead view of rescuers 306 a and 306 bperforming CPR chest compression on the patient 302 using an ACD CPRchest compression system 304. In the illustrated example of FIG. 3 , therescuers 306 a and 306 b are already in position and providing care tothe patient 302, with rescuer 306 a in position and providing chestcompressions to the torso of the patient 302 by using ACD CPR chestcompression system 304, and rescuer 306 b providing ventilation using aventilation bag 307. In some implementations, the configuration andgeometry of the ACD CPR chest compression system 304 enables the rescuer306 a to use the same body position and compression technique as instandard CPR chest compression. In some implementations, the ACD CPRchest compression system 304 is configured to enable the rescuer 306 ato perform active chest decompression by maintaining a firm grip on theACD CPR chest compression system 304 and swinging the body weightupwards after compression. Motion sensors and/or pressure/force sensorsmay be included in the housing of the handle or piston of the ACD CPRchest compression system 304, as further described with reference toFIGS. 5A and 5B.

Feedback may be provided on the elevated decompression phase 26, forinstance, providing and indicator of the amount of force delivered tothe patient's chest by the ACD device during the elevated decompressionphase 26, as measured by a decompression force sensor 532, as shown inFIG. 5B. The decompression force sensor may be configured as acompression sensor such as a load cell (e.g. LBMU Ultra Compression LoadButton, Interface Advanced Force measurement, Scottsdale AZ) with a loadarm 534 that engages with the load cell during decompression. There mayalso be one or more separate compression force/pressure sensors 533 tomeasure the downward force or pressure during the compression phases(e.g. elevated compression, non-elevated compression, and non-elevateddecompression).

Referring to FIG. 5B, sensors such as force sensors 532, 533 areincluded in the housing for measuring the pressures and forces duringthe various phases. Motion sensors such as an accelerometer, gyroscope,etc. may also be located in the housing for measuring the motion of thepatient's sternum during chest compressions, for instance accelerometer534 located at the distal end of the system piston 570, or the motionsensor can be located in the handle, e.g. a motion sensor that may be atilt and off-axis motion sensor 539 that can measure if the rescuer isproperly directing the force and motion vector of the compression anddecompression so that therapy is properly being delivered to thepatient. For instance, it may be preferable for the direction in whichcompression and decompression therapy is administered to besubstantially perpendicular to the sternum of the patient, rather thanat an angle which may otherwise lead to less effective or otherwiseinefficient treatment. Sensors may be powered for example by battery 536and power supply located on circuit board 535, and outputs of thesensors are amplified and signal conditioned using techniques known tothose skilled in the art then digitized by A to D converters andprocessed by a microprocessor to output measurements of the variousphases of the compression cycle. The force and motion sensors may alsobe located in the defibrillation electrodes 204 connected to adefibrillator 312.

Referring back to FIG. 3 , the rescuers 306 a and 306 b can be layrescuers who were in the vicinity of the patient 302 when the patient302 required care, or can be trained medical personnel, such asemergency medical personnel (EMTs). Although two rescuers are shown inFIG. 3 , additional rescuers can also care for the patient 302, and canbe included in a rotation of rescuers providing particular components ofcare to the patient 302, where the components can include chestcompressions, ventilation, administration of drugs, and other provisionsof care.

In general, the system 300 includes various portable devices formonitoring on-site care given to the patient 302. The various devicescan be provided by emergency medical personnel who arrive at the sceneand who provide care for the patient 302, such as rescuers 306 a and 306b. The onsite rescuers 306 a and 306 b can be assisted by remote medicalpersonnel 308, located at a medical facility 314 within a healthcarenetwork. In the illustrated example, the rescuers 306 a and 306 b useseveral devices to provide an emergency treatment to the patient 302.

The devices used by the rescuers 306 a, 306 b, and/or the medicalpersonnel 308 during CPR chest compression can include the ACD CPR chestcompression system 304 and a portable defibrillator 312. A visualmetronome can guide the rescuer 306 a to perform each phase of ACD CPRchest compression treatment at the appropriate rate and force. The ACDCPR chest compression system 304 can be a standalone device that isplaced on the patient's chest (as illustrated in FIG. 3 ). The ACD CPRchest compression system 304 can also be attached to another device usedby the medical personnel during CPR chest compression, such as theportable defibrillator 312. The attachment of the ACD CPR chestcompression system 304 with other devices can enable synchronization ofmultiple CPR-related procedures (e.g. ventilations, defibrillation,etc.).

In addition to the ACD CPR chest compression system 304, FIG. 3 shows aportable defibrillator 312 and ancillary components arranged to providefeedback and instruction to rescuers 306 a and 306 b. FIG. 3 shows anexample in which visual feedback can be provided to the rescuer 306 afrom a location that is away from the defibrillator unit, and moreimmediately in the line of sight and focus of attention of the rescuer306 a, such as a graphical user interface of a local feedback display onthe ACD CPR chest compression system. Referring to FIG. 5A, the localfeedback display 537 may take the form of a bar graph, or provide moresophisticated information via a graphical display such as an LCDcontaining information such as the depth/height meter 3120 shown in FIG.11A.

It can be appreciated that any suitable feedback component may be usedin accordance with the present disclosure. As discussed, the feedbackcomponent may include a user interface, apparatus or other unit thatreceives a feedback signal and generates feedback to assist arescuer/user in providing quality ACD CPR to a patient. Various forms offeedback are described herein, for example, visual feedback involving adisplay interface having textual and/or graphical feedback information,audio feedback from a speaker or other audio device to provide verbal,non-verbal, tonal and/or other audible feedback, haptic feedback whichprovides tactile indications of how the user may adjust the manner inwhich ACD CPR is administered, amongst others.

The portable defibrillator 312 is shown in a deployed state and isconnected to the patient 302. In addition to providing defibrillation,the defibrillator 312 can serve as a patient monitor via a variety ofsensors or sensor packages. For example, as shown here, electrodes 315have been applied to the bare chest of the patient 302 and have beenconnected to the defibrillator 312, so that electrical shocking pulsescan be provided to the electrodes in an effort to defibrillate thepatient 302, and electrocardiogram (ECG) signals can be read from thepatient 302. The defibrillator 312 can provide feedback in aconventional and known manner to an onsite rescuer, such as emergencymedical personnel 306 a and 306 b.

In some implementations, additional therapeutic delivery devices (notshown) can be used to deliver the appropriate therapy to the patient.The therapeutic delivery devices can be, for example, a drug infusiondevice, an automatic ventilator and/or a device that includes multipletherapies such as defibrillation, chest compression, ventilation, anddrug infusion. The therapeutic delivery devices are physically separatefrom the defibrillator 312, and control of the therapeutic deliverydevices can be accomplished by a communications link from thedefibrillator 312 that can be wired, wireless, or both.

In some implementations, control and coordination for the overallresuscitation treatment and the delivery of the various therapies can beaccomplished through optimized chest compressions and decompressions,optionally based on rescuer's profile, by a processor that is integratedin the defibrillator 312 or is external to the defibrillator 312, suchas the computing device 310 that is controlled by remote medicalpersonnel 308. For instance, the computing device 310 can retrieve andprocess signals indicative of ACD CPR chest compression treatment (e.g.,the force applied by the rescuer 306 a through the ACD CPR chestcompression system 304 and/or patient's chest wall displacement relativeto time) and ECG data from the defibrillator 312.

The computing device 310 can analyze the signals to determine one ormore parameters indicative of ACD CPR chest compression treatment. Theparameters can include transition points, applied pressure, motion ofthe patient's chest wall (e.g., patient's chest wall velocity,displacement, and/or acceleration), compliance of patient's chest wall,adherence of the adhesive pad of the ACD CPR chest compression system304, an angle of compression and decompression, and/or other parameters.Transition points define a transition between phases of the ACD CPRchest compression treatment, such as between a non-elevated phase and anelevated phase. The identification that a transition point has beenreached can be determined from at least one of a displacementinformation and a force information.

Force measurements obtained from a force sensor may be processed byitself or in combination with other measurements to provide usefulinformation in assisting the acute care provider in performingresuscitative treatment. For instance, the force measurement can bedirectly converted into pressure data, the surface of the forceapplication being known. In addition, the measurement of patient's chestwall displacement relative to time can be converted into velocitymeasurement. The velocity can be used to determine how long the chest isheld at a particular pressure. The area under the curve of the patient'schest wall velocity can be used as a key factor regarding optimizedblood flow. The displacement measurement of the patient's chest wall andthe force measurement can be used to determine the compliance of thepatient's chest wall, expressed as the distance over force (e.g., cm/N)and represented in terms of an X/Y loop and/or as discrete numbervalues. The adherence degree (or partial separation) of the adhesive padcan be determined by analyzing signals from an accelerometer attached tothe adhesive pad and a second accelerometer attached to the handle. Forexample, a displacement of the adhesive pad recorded while the chestdoes not move, may indicate that the adhesive pad is detached from thepatient's chest wall. The angle of compression and decompression can bedetermined to provide feedback to the user to push and pull indirections perpendicular to the chest. The angle of compression anddecompression can be determined by using multiple force/accelerationsensors placed at various locations within the ACD CPR chest compressionsystem 304. A 3-axis accelerometer may also be used to determine theangles of compression and decompression.

In parallel with analyzing the parameters indicative of ACD CPR chestcompression treatment, the computing device 310 can process ECG signals,and perform relevant determinations to optimize the amplitude and thefrequency of the force applied by the rescuer 306 a and thereforeoptimize ACD CPR chest compression treatment delivery. In someimplementations, the processor integrated in the defibrillator 312 or aprocessor integrated in the ACD CPR chest compression system 304 canperform all the processing of the force applied by the rescuer 306 a ofthe rescuer 306 a and the ECG, and can display a suitable level offeedback to the rescuers 306 a and 306 b. The defibrillator 312 can alsotransmit to a separate device (e.g., ACD CPR chest compression system304) particular sets of processed data, and in response, the separatedevice can perform particular control actions.

An electrode assembly 315 is illustrated as being attached to thepatient 302 in a standard position. The electrode assembly 315, in thisexample, is an assembly that combines an electrode positioned high onthe right side of the patient's torso and an electrode positioned low onthe left side of the patient's torso, along with a sensor packagelocated over the patient's sternum (e.g. ZOLL Medical CPR Stat Padz®,Chelmsford MA). The sensor package, which is obscured in the figure bythe hands of rescuer 306 a in this example, can include an accelerometeror similar sensor package that can be used in cooperation with acomputer in the defibrillator 312 to generate an overall quality scorefor the chest compressions and decompressions, and the quality score canindicate instantaneous quality or average quality across a time. Forexample, as a simplified description, signals from an accelerometer canbe double integrated to identify a vertical displacement of the sensorpackage, and in turn of the sternum of the patient 302, to identify themagnitude of each chest compression and decompression. The time betweenreceiving such input from the sensor package can be used to identify thepace at which chest compressions and decompressions are being applied tothe patient 302.

The defibrillator 312 in this example is connected to the electrodepackage 315 and can operate according to standard protocol (e.g., toprovide defibrillating shocks to the electrode package 315). Thedefibrillator can be a professional defibrillator, such as the R SERIES,M SERIES, E SERIES, or X SERIES from ZOLL Medical Corporation ofChelmsford, MA, or an automated external defibrillator (AED), includingthe AED PLUS, AED PRO, or ZOLL AED 3 from ZOLL Medical Corporation. Thedefibrillator is shown in one position relative to the rescuers 306 aand 306 b here, but can be placed in other locations to better presentinformation to them, such as in the form of lights, displays, vibrators,or audible sound generators on a chest-mounted component such as anelectrode or via an addressable earpiece for each of the rescuers. Suchfeedback, as discussed more fully below, can be on units that areseparate from the main housing of the defibrillator, and that cancommunicate information about the patient 302 and performance of CPRchest compression to the defibrillator 312 or can receive feedbackinformation from the defibrillator 312, through either wired or wirelessconnects that are made directly with the defibrillator 312 or indirectlythrough another device or devices.

In some implementations, the ACD CPR chest compression system 304 andthe defibrillator 312 can be connected to the network 318 to transmitthe acquired data to a computing device 310 that can be operated by theremote medical personnel 308. The CPR chest compression data transmittedby the ACD CPR chest compression system 304 and the defibrillator 312 tothe computing device 310 can include data associated with theperformance of the rescuer 306 a and data associated with the responseof the patient 302 to CPR chest compression. The ACD CPR chestcompression system 304 can send information about the performance ofchest compressions and decompressions, such as depth, rate, force,velocity, work, ventilation parameter(s), and/or other information forthe chest compressions and decompressions. The defibrillator 312 cansend ECG data and information related to characteristics ofdefibrillation signals. The computing device 310 can also receive datafrom the other sensors associated with the patient 302 such as anairflow sensor attached to or otherwise provided with a ventilation bag307.

A central server system 320 can communicate with the computing device310 or other devices at the rescue scene over a wireless network and/ora network 318, which can include portions of the Internet (where datacan be appropriately encrypted to protect privacy). The central serversystem 320 can be provided as a server, or a virtual server, that runsserver software components, and can include data storage including, butnot limited to, a database and/or flat files. The central server system320 can be part of a larger system of a healthcare continuum, in whichpatient data 322 and rescuer profiles 324, 326, and 328 are stored.Patient data 302 can be associated with an identification number orother identifier, and stored by the central server system 320 for lateraccess.

Additionally, the central server system 320 can store patient profilesthat include patient characteristics associated with the ACD CPR chestcompression treatment and one or more parameters descriptive of the ACDCPR chest compression treatment. A patient profile can include age,gender, body-mass index, medical history (e.g., including known bonediseases that can affect rib cage compliance) and other patientcharacteristics relevant in selecting and optimizing the ACD CPR chestcompression treatment. The parameters descriptive of the ACD CPR chestcompression treatment can include parameters descriptive of thecompression and decompression, such as force amplitude, impulse,distance, average force, peak force, etc., that can be calculatedknowing the time of occurrence of the transition between the phases ofthe ACD CPR chest compression treatment.

Users interacting with the system 300 can access the data in the centralserver system 320. For example, as shown in FIG. 3 , medical personnel308, operating a computing device 310 that communicates wirelessly, suchas over a cellular data network can access current and past CPR chestcompression data. As such, the medical personnel 308 can review CPRchest compression data stored in the central server system 320. In thismanner, the system 300 permits various portable electronic devices tocommunicate with each other so as to coordinate and optimize care thatis provided to a patient 302 based on the patient profile treated at therescue scene.

Example system 300 can provide real-time feedback to the rescuers 306 aand 306 b. For example, the defibrillator 312 or a display of acomputing device can provide a prompt to guide the rescuers 306 a and306 b in performing each phase of the ACD CPR chest compressiontreatment. The prompt can include at least one of an audio prompt, averbal prompt, a non-verbal prompt, a visual prompt, a graphical promptand a haptic prompt. Further details about the systems and methods ofproviding the prompt are described in detail with reference to FIG. 6 .The process of observing the quality of a component of the CPR chestcompression, such as the quality of each phase of ACD CPR chestcompression treatment, can continue recursively as long as care is beingprovided to the patient 302. In some implementations, trends in thequality of a particular CPR chest compression component can be trackedso that the defibrillator 312 can distinguish situations, in which arescuer is giving a poor chest compressions and decompressions becausehe or she was trying to find the appropriate rhythm or was distracted bya temporary problem, from situations in which the user truly is tiringand rescuer's position can be optimized.

In some instances, the defibrillator 312 and/or the ACD CPR chestcompression system 304 can be adaptable to different CPR protocols. Forexample, the defibrillator 312 and/or the ACD CPR chest compressionsystem 304 can be programmed according to a protocol that ispersonalized based on one or more parameters, such as patientcharacteristics, patient's medical conditions and patient's response totreatment. Some parameters can be automatically measured and processedby the ACD CPR chest compression system and some parameters can beentered by the rescuers. Protocols can be generally configured based onAHA guidelines. The protocols can include the duration of each phase ofthe ACD CPR chest compression treatment, one or more force parametersthat can be applied during each of the phases (e.g., the forcevariation, force amplitude, force thresholds, and angles for applyingthe force). In some implementations, a rescuer, such as a medicaldirector or an experienced rescuer, can alter such guidelines to fitparticular patient needs, according to professional judgment.

In such a situation, the defibrillator 312 and/or the ACD CPR chestcompression system 304 can be programmed with the parameters for each ofthe protocols, and an operator of the defibrillator 312 can select aprotocol to be executed by the defibrillator 312 (or the protocol canhave been selected by a medical director) and the protocol to beexecuted by the ACD CPR chest compression system 304. Such a selectioncan occur at the time of a rescue, or at a prior time. For example, theability to select a protocol can be differentiated based on accessprivileges, such as a person who runs an EMT service (e.g., a medicaldirector of appropriate training and certification to make such adetermination). A user interacting with the defibrillator 312 and/or theACD CPR chest compression system 304 can select the protocol to befollowed on each of the machines operated by the service, and otherusers can be prevented from making particular changes, if lacking accessprivileges. In this manner, the defibrillator 312 and/or the ACD CPRchest compression system 304 can be caused to match its performance towhatever protocol its users have been trained to.

Using the techniques described here, the defibrillator 112 can, inaddition to providing defibrillation shocks, ECG analysis, and otherfeatures traditionally provided by a defibrillator, also provideindications to optimize the data related to compression anddecompression in real-time and/or to switch rescuers between variouscomponents of providing CPR and other care to a patient. Thedefibrillator can be deployed in the same manner as existingdefibrillators, but can provide additional functionality in a mannerthat can be easily understood by trained and untrained rescuers.

FIGS. 4A and 4B illustrate examples of components of an ACD CPR chestcompression system 400 (e.g., ACD CPR chest compression system 304described with reference to FIG. 3 ) that can be used to deliver a CPRchest compression treatment to the patient 302. The example componentsof the ACD CPR chest compression system 400 can include an adhesive pad402, a coupling surface 404, a sensor 406, and an ACD device 408.

The adhesive pad 402 can include an alignment feature 410. The alignmentfeature 410 can be included in the upward facing portion of the adhesivepad 402. The alignment feature 410 can guide a rescuer in attaching theadhesive pad 402 to an optimal portion of the patient's chest. Theadhesive pad 402 can include a liner 402 a and an adhesive face 402 b.The liner 402 a can be removed or peeled away from adhesive face 402 bby a rescuer to attach the adhesive pad 402 to the patient 302. Theadhesive face 402 b can be configured to be releasably attached to thepatient's chest, for example on the sternum at the mid-nipple line asshown in FIGS. 4A-4D.

The adhesive face 402 b can include a layer of high-traction oranti-slip material for contacting the skin of the patient 302, such thatthe adhesive pad 402 remains attached to the patient's skin during CPRchest compression treatment. In some implementations, the adhesive face402 b can include pressure-sensitive adhesives, such as medical bandageadhesives, transdermal patches, and other medical applications. In someimplementations, the adhesive face 402 b can include natural andsynthetic rubber-based formulations, such as polyisobutylenes, andacrylic and silicon-based materials, and swollen hydrogels, such aspolyvinyl pyrrolidone, which are suitable in conjunction withelectrodes. At completion of a CPR chest compression treatment with theACD CPR chest compression system 400, the adhesive face 402 b can beremoved from the patient's chest.

The dimensions of adhesive pad 402 can be chosen to provide a desiredcontact area with the patient's chest. In some implementations, thelarger the surface of the adhesive pad 402, the more expansion of chestcan be achieved using ACD CPR chest compression system 400 (e.g., if thepatient's chest is compliant or if a rib has been broken). Typically,for adult patients, adhesive pad 402 can have a generally square orrectangular shape. For children, the dimensions can be smaller. Othershapes can also be useful. For example, it can be desirable to shape thelower surface 402 a of the adhesive pad 402 to conform to the generalcontours of the patient's chest. In addition, it may be desirable toprovide a plurality of sizes and shapes of adhesive pads 402 in a singlekit so that an adhesive pad 402 can be selected for the individualpatient 302. The thickness of the adhesive pad 402 can depend on theresiliency of the material employed. For manual CPR chest compressionoperation, the adhesive pad 402 can be about 30 cm by 40 cm.

The adhesive pad 402 can include an electrode configured to transmit adefibrillation current to the patient 302. The adhesive pad 402 caninclude or be coupled to the sensor 406. The sensor 406 can beconfigured to measure at least one chest compression parameter duringCPR chest compression treatment. A wire 416 can provide an electricalconnection between the sensor 406 and a medical device (e.g., thedefibrillator 312 described with reference to FIG. 3 ). For example, thesensor 406 can be used to assess and display the condition of thepatient 302 prior to and during the CPR chest compression treatment. Insome cases, the signals detected by the sensor 406 are used to initiateand optimize the CPR chest compression treatment. Examples of electrodeand sensor configurations are further described with reference to FIG. 6

In some implementations, the coupling surface 404 at least partiallysurrounds the sensor 406 and/or at least a portion of the wire 416. Thecoupling surface 404 can be an integrated part of the adhesive pad 402or it can be releasably attached to the adhesive pad 402. The couplingsurface 402 includes an upward facing portion 404 a and a downwardfacing portion 404 b. The downward facing portion 404 b can beconfigured to maintain adherence with the adhesive pad 402. The upwardfacing portion 404 a can be configured to maintain adherence with theACD device 408. The adherence between the coupling surface 404 and theACD device 408 can be sufficient to transfer a decompression forcebetween the ACD device 408 and the patient's chest during the CPR chestcompression treatment without detaching. The upward facing portion 404 acan be substantially smooth.

The ACD device 408 can include an applicator body 414, a handle 422, anda stem 424. The applicator body 414 can be made of a deformablerubberized material, and it comprises a body portion and a seal portion,which extends integrally from one end of the body portion. Theapplicator body 414 is formed in a substantially circular, rounded,open, cup-shaped configuration so that it has an enlarged open end and areduced end that is attached to the handle 422. An enlarged openinterior area or cavity is formed in the applicator body 414 so that itopens outwardly through the open end. The applicator body 414 is furtherdescribed in detail with reference to FIGS. 5C-5E.

The handle 422 includes a dome-shaped upper surface 422 a and an annularplanar lower surface 422 b separated by a peripheral flange. The top ofstem 424 is centrally located within annular lower surface 422 b of thehandle 422 and the bottom of stem 424 is centrally located on the uppersurface 404 a of the coupling surface 404. The cross-section of theapplicator body 414 defines the dimensions of compressive/decompressivearea, such as landing pad 412. The handle 422 is shaped to enablerescuer's hands to optimally grasp the handle 422 with the palms restingon the upper surface 422 a, the fingers wrapped around ridge of thehandle and the finger tips positioned against lower surface 422 b (FIGS.4C and 4D). Handle 422 and connective stem 424 can be constructed from asuitable rigid material, e.g. a molded plastic. Handle 422 can be filledwith a gel, foam, padding or the like to enhance its shock-absorbing anddistributing capability.

The coupling surface 404 can include a landing pad 412 for theapplicator body 414 of the ACD device 408. The landing pad 412 includesa surface that complements, for example, as size and geometry, theapplicator body 414. In some implementations, the coupling surface 404includes a compliant and resilient material, such as a natural orsynthetic foam. In some implementations, the coupling surface 404includes an attachment member 418 a complementary to a correspondingattachment member 418 b of the ACD device 408. Each of the mechanicalattachment members 418 a and 418 b can include a mating interface. Theattachment members 418 a and 418 b can include mechanical gearing,hydraulics, pneumatics, and/or electromagnetic coupling. For example,the attachment members 418 a and 418 b can form a pneumatic system forincreasing or enhancing a vacuum between the applicator body 414 and thecoupling surface 404. The attachment members 418 a and 418 b can also beconfigured to act as actuators to release the vacuum holds of theattached applicator body 414 from the coupling surface 404, forinstance, by injecting air into the applicator body 414. The attachmentmembers 418 a and 418 b can include well-known components such as apump, valves, and/or fluid transfer lines.

In some implementations, the ACD CPR chest compression system 400includes a passageway 420 located between the sensor 406 and thecoupling surface 404. The passageway 420 can be configured to optimizethe propagation of the compression and decompression forces from the ACDdevice 408 to the patient's chest. The dimensions of passageway 420 canbe chosen to relative to the base of the applicator body 418 and thesurface of the sensor 406. For example, the passageway 420 cansubstantially encircle the sensor 406, such that the inner diameter ofthe passageway 420 is at least equal or larger than the outer diameterof the sensor 406. The passageway 420 can be completely encircled by thebase of the applicator body 418, such that the outer diameter of thepassageway 420 is at least equal or smaller than the inner diameter ofthe base of the applicator body 418. The passageway 420 can havemultiple configurations and structures.

FIGS. 4C and 4D illustrate a perspective view of the ACD CPR chestcompression system 400, in which the ACD device 408 is attached to thecoupling surface 404. The illustrated arrangement of the ACD CPR chestcompression system 400 can be used by a rescuer (e.g., 306 a describedwith reference to FIG. 3 ) for performing both active compressions (FIG.4C) and decompressions (FIG. 4D) for manual CPR chest compressiontreatment. The configuration of the ACD device 408 enables the rescuer306 to press down on upper surface 422 a of handle 422 with the palms ofthe hands to apply a compressive force against coupling surface 404 andpatient's chest over a compressive/decompressive area, such as landingpad 412. The configuration of the ACD device 408 also allows theoperator to lift up by pressing on the lower surface 422 b of the handle422 with the fingers. Since lower surface 402 a of adhesive pad 402 isadhered to contact area of patient's chest, the lifting motion on handle422 lifts and expands patient's chest.

FIG. 5A illustrates a top view of an ACD device 500 (e.g., ACD device208 in FIG. 4A). The ACD device 500 includes a handle 510 and anapplicator body 530. The handle 510 has two handgrips 510 a, 510 b and alocal feedback display 537. The ACD device 500 can be configured forbeing used to assist with multiple CPR chest compression treatments. TheACD device 500 can be switched on and turned off by pressing and holdingdown the power button 502 for a predetermined amount of time, forexample 5 seconds. During this time, the local feedback display 537 candisplay the remaining battery life in time units (e.g., hours). If thepower button is not held for a sufficient amount of time (e.g. 5seconds) the ACD device 500 can remain on, and it automatically poweroff after 5 minutes if no compressions are sensed.

The ACD device 500 can be configured to provide a predetermined numberof hours of use. For example, the ACD device 500 can be designed toprovide about 30 hours of use. At any time, a rescuer can determine theremaining battery life by pressing and holding a power button. The localfeedback display 537 can display the amount of time remaining, forexample by displaying the letter H followed by a number. The number canindicate the number of hours of battery life remaining. In someimplementations, the local feedback display 537 can display an alertwhen the ACD device 500 has less than one hour of battery liferemaining.

The handle 510 is attached to the applicator body 530. The applicatorbody 530 can be releasably attached to a coupling surface 522 (e.g.,coupling surface 404 described with reference to FIG. 4A) that isattached via a contact adhesive 523 to the patient's skin 520. In someimplementations, the applicator body 530 can be attached to the couplingsurface 522 via a magnet. In some implementations, the magnetic couplingis configured such that applicator body 530 becomes detached fromcoupling surface 522 when excessive decompression force (upward pull) isapplied. Other means to couple the applicator body 530 to the couplingsurface 522 include various mechanical connections including ball andsocket, cantilevered arm, or detent mechanism or the like.

FIG. 5B illustrates an example of a magnetic coupling mechanism in anexternal chest compression and decompression system. FIG. 5B provides across-section view of compression and decompression the ACD device 500,which includes an applicator body 530 releasably coupled to the couplingsurface 522, which is attached to an adhesive pad 522 that is attachedto the patient's skin 520. The ACD device 500 can include a plurality ofsensors 532, 533, 534 and 539, a processor circuit 535 containing, e.g.,the sensor signal acquisition, microprocessor, power supply,communications, etc., other electronics, a battery 536, a local feedbackdisplay 537, a coupling mechanism 550 between the coupling surface 522and the applicator body 512. Sensor 532 can be a decompression forcesensor. Sensor 533 can be a compression force sensor. Sensor 534 can bean accelerometer or other type of motion sensor. Sensor 539 can be atilt and off axis motion sensor. Each of the plurality of sensors 532,533, 534 and 539 can generate signals to monitor and optimize ACD CPRchest compression treatment (e.g., by assisting with identification ofdifferent treatment phases and transition points, as described withreference to FIG. 1 ). The measurements of the signals detected by thesensors 532, 533, 534 and 539 can be displayed on the local feedbackdisplay 537, as illustrated in FIG. 11A.

The coupling mechanism 560 can include a magnet 540 and a magnet keeper550. In some implementations, the magnet 540 can include or be part of amagnet assembly having a magnet, a non-ferrous spacer, and a ferrouscontainer for directing the magnetic flux from the pole of the magnetfurthest away from the magnet keeper to the magnet keeper. The poles ofthe magnet can be arranged such that the poles are aligned along theaxis 580 of the system piston 570. The magnetic keeper 550 on thecoupling surface 522 of the ACD device 500 can include a magnet withpoles arranged in the opposite direction of the system handle magnet orof a ferrous material such as 12L14 carbon steel having a high capacityfor carrying magnetic flux. A magnetic coupling between the applicatorbody 530 and the coupling surface 522 can be effortless. In someimplementations, the force of the disconnection of the magnetic couplingcan be stable over a wide range of operating environments.

In some implementations, a magnetic coupler mechanism 518 can include amagnet assembly disposed on or coupled with the applicator body 530, anda keeper assembly disposed on or coupled with the coupling surface 522.For example, a magnetic coupler mechanism 518 can include magnet 540, ormagnet assembly, and keeper assembly 550. The magnet 540 or magnetassembly can be coupled with (or part of) the applicator body 530. Thekeeper assembly 550 can be coupled with or part of the coupling surface522. The magnet assembly and keeper assembly 550 in combination can bereferred to as a coupler assembly. In some implementations, the couplerassembly can operate to provide a consistent release force allowing theapplicator body 530 to separate from the coupling surface 522 prior tothe adhesive pad releasing from the patient' skin 520. In addition, itmay be desirable that the magnet assembly does not have a magnetic fieldthat is widely dispersed, but approximately focused in the direction ofthe keeper. To focus the magnetic field, the magnet assembly can includea magnetic core, a non-magnetic sleeve, and a ferromagnetic pot whichconducts the magnetic flux from the pole on the enclosed side of themagnet to the open side of the magnet. The arrangement of a jacket withthe magnet can focus the majority of the magnetic flux to the open endof the assembly. For example, the magnet assembly may include a magneticore 540, a non-magnetic sleeve, and a ferromagnetic pot, which conductsthe magnetic flux from the pole on the enclosed side 540 of the magnetto the open side 540 of the magnet. The arrangement of a jacket with themagnet can focus the majority of the magnetic flux to the open end ofthe assembly. Control or selection of the material properties of thekeeper 550 can be helpful to achieve a consistent release force. In someimplementations, the material can have a high magnetic saturation suchas a 12L14 or American Iron and Steel Institute (AISI) 1010 or 1020material and the magnetic properties of the material can be controlledthrough the control of material temper. For example, materials can beprocessed to a fully annealed condition. In addition to the magneticcoupling mechanism described herein, other types of breakaway mechanismscan be used in an external chest compression and decompression forcoupling the coupling surface 522 with the ACD device 500. Examples ofbreakaway mechanisms can be configured to allow the ACD device 500 todisengage from the coupling surface 522 in a controlled manner.

FIGS. 5C-5E illustrate examples of bottom views of the ACD device 500.The bottom views include the applicator body 530 of the ACD device 500(e.g., applicator body 214 of the ACD device 208 described withreference to FIG. 2 ). In some implementations, the applicator body 530can be a plunger. The applicator body 530 includes a distal end 592 anda proximal end 594. The proximal end 594 defines the part of theapplicator body 530 that extends from the applicator body 530. Thedistal end 592 defines the part of the applicator body 530 that impactsthe patient's chest through the coupling surface 522. The applicatorbody 530 can include one or more check valves allowing fluid to escapethe passageway during attachment to the coupling surface 522, butpreventing fluid from entering the passageway via the check valves. Thecheck valves include one or more of duckbill valves, umbrella valves,cross slit valves, ball-check valves, cone-check valves, and swingvalves.

In some implementations, the applicator body 530 includes a compressionpad 596. The compression pad 596 can be a flexible surface elementconfigured to regulate the force applied to the patient's chest throughthe air passageway of the coupling surface. The compression pad 596 caninclude an adhesive layer. The compression pad 596 can include one ormore suction cups 598 that apply compression and decompression forces topatient's chest through the coupling surface 522. The adhesive layer canline the margins of the suction cups 598. The compression pad 596 can besecured to the coupling surface 522 by suction created by the suctioncups 598 formed on distal end 592. A rescuer can pull back the ACDdevice 500, which in response extends the applicator body 530, toconfirm secure coupling between the compression pad 596 and the couplingsurface 522.

The compression pad 596 has a stiffness that increases from marginstowards a geometrical center of the compression pad 596. The compressionpad 596 can present any suitable complex shape, including multipleappendages, arms or lobes. Each arm or lobe of the compression pad 596can contain numerous suction cups 598. The use of multiple lobes enablesthe compression pad 596 with many suction cups 598 to conform toirregularities in the top layer of the coupling surface 522 (e.g.,irregularities due to sensor and wire inclusions). The lobes of thecompression pad can be conformable and inelastic to convey thedecompression force between ACD device 500 and the coupling surface 522.

In some implementations, the size and/or shape of the suction cups 598can be selected based on one or more characteristics of the couplingsurface 522. In some implementations, the number and the location of thesuction cups 598 can be selected based on one or more characteristics ofthe coupling surface 522. For example, the suction cups 598 can bearranged in two groups 598 a and 598 b, distanced from each other, suchthat no suction cup covers the passageway of the coupling surface 522during coupling between the compression pad 596 and the coupling surface522.

Referring to FIG. 6 , an example system 600 is shown in which adefibrillator 602, including a standard configuration, is upgraded toprovide an additional user feedback functionality. The defibrillator 602is connected to an electrode assembly by way of a wiring harness 604.The wiring harness 604 can include a number of wire leads that areconnected together by a common plastic shroud that can surround thewires or can have been integrally formed around the wires such asthrough an extrusion process, and can be connected to the defibrillator602 by way of a single plug. For example, the defibrillator 602 can beprovided with a female or male connection, and the plug can be providedwith a corresponding connection in a manner that is well known in theart. The wires can carry power from the defibrillator 602, such ascurrent to provide a shock to a patient who is being provided withemergency care, or to the defibrillator 602, such as in the form ofsignals for generating ECG information, accelerometer information, andmeasurements of trans-thoracic impedance of a patient.

The electrode assembly in this example includes a first electrode 606, asecond electrode 608, and a chest compression assembly 610. The firstelectrode 606 can be configured to be placed above the patient's rightbreast, while the second electrode 608 can be configured to be placedbelow the patient's left breast. During a rescue operation, printedinsignia on one or both of the electrodes 606, 608 can indicate to arescuer how to deploy the electrodes 606, 608, and where each of themcan be placed. In addition, the defibrillator 602 can display suchinstructions on a graphical display and can also provide verbalinstructions to supplement was is shown in the visual instructions, suchas instructions for the sequential operation of the defibrillator.

The chest compression assembly 610, in this example, includes a detector612 and a display 614. The detector 612 can include a plastic housingwithin which is mounted an accelerator assembly. The acceleratorassembly can move with the housing as chest compressions anddecompressions are performed on a patient so that motion of theaccelerometer matches motion of the patient's sternum. The detector 612is shown in the figure as having an “X” printed on its top surface toindicate to the rescuer where to place his or her hands when deliveringchest compressions and decompressions to a patient. The accelerator inthe housing can be connected to pass signals through harness 604 todefibrillator 602 (or can include a wireless transceiver for passing theinformation wirelessly), which can be provided with circuitry and orsoftware for converting such signals into the indications about the rateand depth of compressions and decompressions being performed on thepatient, in manners such as those described below.

The display 614 can provide feedback that is directed to the rescuer whois performing chest compressions and decompressions. In this example,the feedback comprises symbols similar to those shown on the display ofdefibrillator 112 in FIG. 1 , in particular, a real-time representationof the rescuer who performs chest compressions and decompressionssynchronously displayed with an optimized rescuer position. Therepresentation can be selected to be independent of the orientation fromwhich it is viewed, so that it has the same meaning to a rescuer who ison the right side of the patient as to a rescuer who is on the left sideof the patient. In that manner, the system 600 does not need todetermine where the rescuer is positioned. Also, a haptic vibratingmechanism can be provided at the assembly 610, so as to provide tactilebeats or metronomes for a user to follow in providing chest compressionsand decompressions.

FIG. 7 shows example chest compression inputs and mechanisms foranalyzing the inputs to determine whether a different rescuer canprovide chest compressions and decompressions. In general, theillustrated example includes a series of eighteen chest compressions anddecompressions 700 that have been graphed along a horizontal time axis,along with a variety of numbers that represent parameters of how thechest compressions and decompressions were performed. Such sensedcompression data and derived numbers can then be used to determine whenthe quality of the chest compressions and decompressions indicates thatthe rescuer is getting fatigued and cannot maintain the optimized CPRchest compression technique identified by the system, and the system canindicate to the rescuer that they can switch with another, fresherrescuer.

Referring more specifically to the graphed compressions anddecompressions, a dashed line 702 represents a target chest compressiondepth. Each of the spikes 704 indicate a distance level of downwardcompression (y axis), graphed according to time (x axis). In particular,the compressions and decompressions are sharp motions followed bypauses, with the overall pattern repeated eighteen times during the time(which can be a fraction of a minute when the rescuer is performingabout 100 compressions and decompressions per minute). Such compressionsand decompressions can be sensed by an accelerometer assembly that isbetween the hands of the rescuer performing chest compressions anddecompressions and the sternum of the patient. Sensed signals can thenbe passed through a wiring harness to circuitry and software in adefibrillator or other medical device that can analyze the signals toidentified compression depths and timing of the chest compressions anddecompressions.

As can be seen, the initial chest compressions and decompressions are atan appropriate level and an appropriate rate, but began to dip at thefourth and fifth compressions and decompressions. The compressions anddecompressions then pick up and hit the dashed line 702, perhaps becausethe fall in compressions and decompressions caused a defibrillator toindicate to a rescuer that they can compress harder, and the userfollowed such direction. The depth of compressions and decompressionsover time then falls again at compressions and decompressions 11, 12 and13, but then picks up at 14 and falls yet again near the end, indicatingthat the user has become fatigued.

Below the graph are shown numbers that, for this example, indicatevalues that can be computed by a defibrillator that is connected to asystem for determining when to signal that a provider of chestcompressions and decompressions to a patient can be changed by thesystem. The top row shows a score that can be given to a user to ratethe quality of the depth of the chest compressions and decompressions.Such a score can be given a baseline of 100 around a depth thatapproximates the desired line of 702. The score can decreaseproportional with the distance from line 702. The score can decreasefaster for deviations on the under-compression side than for deviationson the over-compression side, e.g., if a determination is made thatunder-compression is a more serious error than over-compression. Thus,for example, the fifth compression falls below line 702 by an amountless than the sixth compression falls above the line, but the fifthcompression receives a lower score than does the sixth compression.

In this example, the depth of compression factor is provided 70% of aweighting in determining an overall score for the quality of the chestcompression. The other 70% of the score is driven by the rate at whichthe user provides the compressions and decompressions. For example, thefeedback can display even spacing for compressions two through eight,but a slight delay for compression nine, so that the ninth compressionreceives a score of 90 instead of a score of 100. In addition, one cansee lengthening delays between compressions and decompressions at theend of the period. The rate scores reflect, in each instance, how far acompression was performed from the time at which it was supposed to beperformed according to protocol. Again, the scores are scaled to amaximum of 100 for ease of explanation, but could take other forms also.

The third line in the numbers indicates an overall score for each of thecompressions and decompressions, where the overall score is simply thecombined weighted value of the two component scores for depth and rate,respectively. Finally, the fourth line shows a running score that is arunning average of the current score and the two previous scores. Byusing a running average, singular deviations from a perfect compressioncan be ignored, while lingering deviations can be captured so thatcontinual failure by a user, which indicates fatigue of the user, canresult in the generation of a signal to switch users in performing chestcompressions and decompressions. Thus, for example, compression numberfive is a bad compression, but the running score is relatively highbecause the previous two compressions and decompressions were better.

In this example, the trigger for generating an indication that users canchange position is a running score at or below 85. Thus, although therunning score in the example rises and falls as a user has periodicproblems with performing compressions and decompressions, it does notfall to the triggering level until compression eighteen, after there hadbeen three weak compressions and decompressions in a row that were alsospaced too far apart—so that the running average score really fell. Inactual implementation, software can monitor the value as a user providescompressions and decompressions, can periodically update the value(e.g., once for each compression or on another basis), and can cause adefibrillator, such as defibrillator 112, to emit output to one or morerescuers to indicate the need for a change, such as the indication shownin the prior figures above.

While the particular running average scoring technique described isprovided for its simplicity and ease of understanding, differentapproaches can be used to identify when a user is likely becoming toofatigued to maintain quality chest compressions and decompressions orother components of CPR chest compression. For example, various inputscan be subjected to derivations in order to determine rates of change ofthose inputs. An indication to change rescuers can be generated when therate of change in the quality of performance exceeds a preset amount ina negative direction. Also, models can be generated to representfatigued users, and actual inputs can be compared to such models toindicate when fatigue is setting in for a real user and to cause analert to be generated.

In some instances, such as when the number of rescuers is known, datacan be stored across multiple cycles of chest compression sessions foreach of the users. For example, the system can identify in early cyclesof a rescue that one of the rescuers has a sudden drop-off in chestcompression performance but then recovers, and can store suchunderstanding and use it in subsequent cycles so as to not trigger anindication to change rescuers simply because the particular rescuer ishaving momentary problems. Another rescuer can be seen to have a slowerdrop in performance but can be more erratic in his provision of chestcompressions and decompressions, so that a system can permit morevariability before it triggers an indication to switch rescuers, sincevariability by that user can not indicate fatigue, but can simply bestandard variability in the manner in which the user performs chestcompressions and decompressions. Other factors can also be taken intoaccount in addition to depth and rate of providing chest compressionsand decompressions. For example, a heart rate monitor can be applied toa rescuer and an increase in heart rate can indicate fatigue by therescuer, and can be used to generate a signal to switch rescuers. Also,the shape of a compression profile can be used, such that a jerky orsharp profile can indicate fatigue by a user, and also contribute to thetriggering of a signal to switch rescuers.

As illustrated in FIG. 8 a defibrillator or a computing device includinga display can provide real-time feedback to the rescuers. In general,the real-time feedback varies depending on an identified phase of thephases of ACD CPR chest compression treatment, e.g., one of the phasesdescribed above with respect to FIG. 1 and FIG. 2 . That is, thefeedback provided to the user or other device may be phase-specific,where the particular type of feedback is relevant for the specific phaseof ACD therapy, according to a predetermined treatment protocol. Forexample, one type of feedback may be displayed if one phase has beendetected, and another type of feedback may be displayed if a differentphase has been detected (e.g., a transition point is detected). Feedbackassociated with a particular phase (e.g., data representing a templatefor a type of feedback to be displayed on a user interface) can bestored in data storage or associated memory and retrieved when the nextphase is detected. For example, the data representing the feedback canbe stored in the storage device 1330 described below with respect toFIG. 13 . Hence, according to a suitable treatment protocol, when thesystem detects ACD therapy to be in a first phase, the system mayretrieve from memory the feedback specific to the first phase andprocess data from the sensor(s) according to the phase-specificfeedback. Similarly, when the system detects ACD therapy to be in asecond phase, following the first phase, the system may retrieve frommemory the feedback specific to the second phase and process data fromthe sensor(s) according to the phase-specific feedback.

For illustrative purposes, two particular examples of feedback are shownon a display 802 of the defibrillator 112. FIG. 8 shows a defibrillatorshowing some types of information that can be displayed to a rescuer. Inthe figure, a defibrillation device 800 with a display portion 802provides information about patient status and CPR chest compressionadministration quality during the use of the defibrillator device. Asshown on display 802, during the administration of chest compressionsand decompressions, the device 800 displays information about the chestcompressions and decompressions in box 814 on the same display as isdisplayed a filtered ECG waveform 810 and a CO2 waveform 812(alternatively, an SpO2 waveform can be displayed).

During chest compressions and decompressions, the ECG waveform isgenerated by gathering ECG data points and accelerometer readings, andfiltering the motion-induced (e.g., CPR chest compression-induced) noiseout of the ECG waveform. Measurement of velocity or acceleration ofchest compression during chest compressions can be performed accordingto the techniques taught by U.S. Pat. No. 7,220,335, entitled “Methodand Apparatus for Enhancement of Chest Compressions during ChestCompressions,” the contents of which are hereby incorporated byreference in their entirety. Displaying the filtered ECG waveform helpsa rescuer reduce interruptions in CPR chest compression because thedisplayed waveform is easier for the rescuer to decipher. If the ECGwaveform is not filtered, artifacts from manual chest compressions anddecompressions can make it difficult to discern the presence of anorganized heart rhythm unless compressions and decompressions arehalted. Filtering out these artifacts can allow rescuers to view theunderlying rhythm without stopping chest compressions anddecompressions.

The CPR chest compression information in box 814 is automaticallydisplayed when compressions and decompressions are detected by adefibrillator. The information about the chest compressions anddecompressions that is displayed in box 814 includes rate 818 (e.g.,number of compressions and decompressions per minute) and depth 816(e.g., depth of compressions and decompressions in inches ormillimeters). The rate and depth of compressions and decompressions canbe determined by analyzing accelerometer readings, or measurements fromother sensor sources. Displaying the actual rate and depth data (inaddition to, or instead of, an indication of whether the values arewithin or outside of an acceptable range) can also provide usefulfeedback to the rescuer. For example, if an acceptable range for chestcompression depth is 2.0 to 2.4 inches, providing the rescuer with anindication that his/her compressions and decompressions are only 1.0inch can allow the rescuer to determine how to correctly modify his/heradministration of the chest compressions and decompressions (e.g., he orshe can know how much to increase effort, and not merely that effort canbe increased some unknown amount).

The information about the chest compressions and decompressions that isdisplayed in box 814 also includes a perfusion performance indicator(PPI) 820. The PPI 820 is a shape (e.g., a diamond) with the amount offill that is in the shape differing over time to provide feedback aboutboth the rate and depth of the compressions and decompressions. When CPRchest compression is being performed adequately, for example, at a rateof about 100 compressions and decompressions per minute (CPM) with thedepth of each compression greater than 40 mm, the entire indicator willbe filled. As the rate and/or depth decreases below acceptable limits,the amount of fill lessens. The PPI 820 provides a visual indication ofthe quality of the CPR chest compression such that the rescuer can aimto keep the PPI 820 completely filled.

As shown in display 802, the filtered ECG waveform 810 is a full-lengthwaveform that fills the entire span of the display device, while thesecond waveform (e.g., the CO2 waveform 812) is a partial-lengthwaveform and fills only a portion of the display. A portion of thedisplay beside the second waveform provides the CPR chest compressioninformation in box 814. For example, the display splits the horizontalarea for the second waveform in half, displaying waveform 812 on left,and CPR chest compression information on the right in box 814.

The data displayed to the rescuer can change based on the actions of therescuer. For example, the data displayed can change based on whether therescuer is currently administering CPR chest compressions anddecompressions to the patient. Additionally, the ECG data displayed tothe user can change based on the detection of CPR chest compressions anddecompressions. For example, an adaptive filter can automatically turnON or OFF based on detection of whether CPR chest compression iscurrently being performed. When the filter is on (during chestcompressions and decompressions), the filtered ECG data is displayed andwhen the filter is off (during periods when chest compressions anddecompressions are not being administered), unfiltered ECG data isdisplayed. An indication of whether the filtered or unfiltered ECG datais displayed can be included with the waveform.

Also shown on the display is a reminder 821 regarding “release” inperforming chest compression. Specifically, a fatigued rescuer can beginleaning forward on the chest of a patient and not release pressure onthe sternum of the patient at the top of each compression. This canreduce the perfusion and circulation accomplished by the chestcompressions and decompressions. The reminder 821 can be displayed whenthe system recognizes that release is not being achieved (e.g., signalsfrom an accelerometer show an “end” to the compression cycle that isflat and thus indicates that the rescuer is staying on the sternum to anunnecessary degree). Such a reminder can be coordinated with otherfeedback as well, and can be presented in an appropriate manner to getthe rescuer's attention. The visual indication can be accompanied byadditional visual feedback near the rescuer's hands, and by a spoken ortonal audible feedback, including a sound that differs sufficiently fromother audible feedback so that the rescuer will understand that release(or more specifically, lack of release) is the target of the feedback.For example, the defibrillator 112 can emit a sound through speaker 822in the form of a metronome to guide the rescuer 106 a in the proper rateof applying CPR chest compression.

With feedback provided at the rescuer's hands, and because the rescuer106 a is providing the chest compressions and decompressions directlywith the hands, input by the system into the hands can be more directlyapplied with respect to the rescuer 106 a keeping an appropriate pace.Such haptic feedback can also relieve the rescuer 106 a of having toturn the head to view the display on defibrillator 112. Thus, a firsttype of feedback, such as pulsed visual, audible, or tactile feedbackcan be provided to guide a user in performing CPR chest compression, andthat type of feedback can be interrupted and replaced with a differenttype of feedback such as constant sound or vibration to indicate that arescuer is to correct a particular component of CPR chest compression(e.g., body position).

FIGS. 9A-9C show example screens that can be displayed to a rescuer on adefibrillator. Each of the displays can be supplemented with a displaylike box 602 in FIG. 6 when the defibrillator determines that rescuersproviding some component of care (e.g., chest compressions anddecompressions) can be changed.

FIG. 9A shows exemplary information displayed during the administrationof CPR chest compressions and decompressions, while FIGS. 9B and 9C showexemplary information displayed when CPR chest compressions anddecompressions are not being sensed by the defibrillator. Thedefibrillator automatically switches the information presented based onwhether chest compressions and decompressions are detected. An exemplarymodification of the information presented on the display can includeautomatically switching one or more waveforms that the defibrillatordisplays. In one example, the type of measurement displayed can bemodified based on the presence or absence of chest compressions anddecompressions. For example, CO2 or depth of chest compressions anddecompressions can be displayed (e.g., a CO2 waveform 920 is displayedin FIG. 9A) during CPR chest compression administration, and upondetection of the cessation of chest compressions and decompressions, thewaveform can be switched to display a SpO2 or pulse waveform (e.g., aSpO2 waveform 922 is displayed in FIG. 9B).

Another exemplary modification of the information presented on thedisplay can include automatically adding/removing the CPR chestcompression information from the display upon detection of the presenceor absence of chest compressions and decompressions. As shown in FIG.9A, when chest compressions and decompressions are detected, a portion924 of the display includes information about the CPR chest compressionsuch as depth 926, rate 928, and PPI 930. As shown in FIG. 9B, when CPRchest compression is halted and the system detects the absence of CPRchest compressions and decompressions, the defibrillator changes the CPRchest compression information in the portion 924 of the display, toinclude an indication 932 that the rescuer can resume CPR chestcompression, and an indication 934 of the idle time since chestcompressions and decompressions were last detected. In a similar manner,when the defibrillator determines that rescuers can change, the label932 can change to a message such as “Change Who is AdministeringCompressions.” In some implementations, as shown in FIG. 9C, when CPRchest compression is halted, the defibrillation device can remove theportion of the display 924 previously showing CPR chest compression dataand can display a full view of the second waveform. Additionally,information about the idle time 936 can be presented on another portionof the display.

FIGS. 10A and 10B show defibrillator displays that indicate to a rescuerlevels of perfusion being obtained by chest compressions anddecompressions that the rescuer is performing. FIG. 10A shows exemplarydata displayed during the administration of CPR chest compressions anddecompressions when the CPR chest compression quality is withinacceptable ranges, while FIG. 10B shows modifications to the displaywhen the CPR chest compression quality is outside of the acceptablerange.

In the example shown in FIG. 10B, the rate of chest compressions anddecompressions has dropped from 80 compressions and decompressions perminute (FIG. 10A) to 60 compressions and decompressions per minute. Thedefibrillator device determines that the compression rate of 108compressions and decompressions per minute is below the acceptable rangeof greater than 100 compressions and decompressions per minute. In orderto alert the user that the compression rate has fallen below theacceptable range, the defibrillator device provides a visual indication1018 to emphasize the rate information. In this example, the visualindication 1018 is a highlighting of the rate information. Similarvisual indications can be provided based on depth measurements when thedepth of the compressions and decompressions is shallower or deeper thanan acceptable range of depths. Also, when the change in rate or depthindicates that a rescuer is becoming fatigued, the system can display amessage to switch who is performing the chest compressions anddecompressions, and can also emit aural or haptic feedback to the sameeffect.

In the examples shown in FIGS. 10A and 10B, a perfusion performanceindicator (PPI) 1016 provides additional information about the qualityof chest compressions and decompressions during CPR chest compression.The PPI 1016 includes a shape (e.g., a diamond) with the amount of fillin the shape differing based on the measured rate and depth of thecompressions and decompressions. In FIG. 10A, the depth and rate fallwithin the acceptable ranges (e.g., at least 100 compressions anddecompressions/minute (CPM) and the depth of each compression is greaterthan 40 mm) so the PPI indicator 1016 a shows a fully filled shape. Inanother example, in FIG. 10B, when the rate has fallen below theacceptable range, the amount of fill in the indicator 1016 b is lessenedsuch that only a portion of the indicator is filled. The partiallyfilled PPI 1016 b provides a visual indication of the quality of the CPRchest compression is below an acceptable range.

As noted above with respect to FIG. 6A, in addition to measuringinformation about the rate and depth of CPR chest compressions anddecompressions, in some implementations the defibrillator providesinformation about the active decompression. For example, as a rescuertires, the rescuer can begin leaning on the patient between chestcompressions and decompressions such that the chest cavity is not ableto fully expand at the end of a compression. If the rescuer does notproperly perform (portions of) chest compressions and/or decompressionsthe quality of the CPR chest compression can diminish. As such,providing a visual or audio indication to the user when the user doesnot fully release can be beneficial. In addition, such factors can beincluded in a determination of whether the rescuer's performance hasdeteriorated to a level that the rescuer can be instructed to permitsomeone else perform the chest compressions and decompressions, and suchinformation can be conveyed in the various manners discussed above.

As shown in FIG. 11A, a visual representation of CPR chest compressionquality can include an indicator of CPR compression-decompressionparameters, such as a CPR chest compression depth/height meter 1120 anda CPR chest compression information box 1124. The CPR chest compressiondepth/height meter 1120 can be automatically displayed upon detection ofCPR chest compressions and decompressions.

On the CPR chest compression depth/height meter 1120, a generalinstruction 1137 can be displayed to visually indicate an instantaneousaction to be administered through the ACD CPR chest compressiontreatment at a particular time. That is, based on the sensed informationfrom the ACD device, the system may provide feedback to the rescuerand/or other device for administering ACD therapy in a desirable manner,to provide as favorable patient outcomes as possible. As shown, the CPRchest compression depth/height meter 1120 may include a display that ispartitioned into sections for certain phases of the ACD CPR chestcompression treatment, to assist a rescuer in providing optimal therapy.For example, the system may assist the user in reaching a target release1136 or a target depth 1140, by highlighting specific instructions foreach phase. For example, the display may highlight prompts such as liftmore 1135 or too shallow 1133 corresponding to the target release 1136.Or, the display may provide prompts including qualitative ACD CPRfeedback, such as “good” 1131 or “too deep” 1132 when guiding therescuer in reaching the target depth 1140. The CPR chest compressiondepth/height meter 1120 can be configured to display identification of atransition point 1134, to indicate the transition between differentphases of the ACD CPR chest compression treatment.

While the example shown in FIG. 11A displayed the target release 1136and target depth 1140 as written instructions, in some additionalexamples, the target values can be displayed as a color or bar codecorresponding to the range of preferred depths and heights. For example,multiple bars can be included on the depth meter 1120 providing anacceptable range of compression depths (e.g., as shown in FIG. 11B) andan acceptable amplitude of decompression heights. Additionally, in someimplementations, compressions and decompressions that have amplitudesoutside of an acceptable range can be highlighted in a different colorthan compressions and decompressions that have depths within theacceptable range of compression depths.

The CPR chest compression information box 1124 is automaticallydisplayed when compressions and decompressions are detected by adefibrillator. The information about the chest compressions anddecompressions that is displayed in box 1124 includes rate 1128 (e.g.,number of compressions and decompressions per minute) and displacement1126 (e.g., depth of compressions expressed as negative values andamplitude of decompressions expressed as positive values in inches ormillimeters). The rate and depth of compressions and decompressions canbe determined by analyzing accelerometer readings. Displaying the actualrate and displacement data (in addition to, or instead of, an indicationof whether the values are within or outside of an acceptable range) canalso provide useful feedback to the rescuer. For example, if anacceptable range for chest compression depth is 25 to 60 mm, providingthe rescuer with an indication that his/her compressions anddecompressions are only 15 mm can allow the rescuer to determine how tocorrectly modify his/her administration of the chest compressions anddecompressions (e.g., he or she can know how much to increase effort inreaching optimal compression and decompression thresholds).

The information about the chest compressions and decompressions that isdisplayed box 1124 also includes a perfusion performance indicator (PPI)1130. The PPI 1130 is a shape (e.g., a diamond) with the amount of fillthat is in the shape differing over time to provide feedback about boththe rate and depth of the compressions and decompressions. When CPRchest compression is being performed adequately within a range ofdesired parameters, for example, at a rate suitable for activecompression decompression such as of about 80 compressions anddecompressions per minute (CPM) with the depth of each compressionfalling within a desirable range for active compression decompression,the entire indicator will be filled. As the rate and/or depth fallsbelow or exceeds above acceptable limits, the amount of fill lessens.The PPI 1130 provides a visual indication of the quality of the CPRchest compression such that the rescuer can aim to keep the PPI 1130completely filled.

In some additional embodiments, physiological information (e.g.,physiological information such as end-tidal CO2 information, arterialpressure information, volumetric CO2, pulse oximetry (presence ofamplitude of waveform possibly), and carotid blood flow (measured byDoppler) of the patient (and in some cases, the rescuer) can be used toprovide feedback on the effectiveness of the CPR chest compressiondelivered at a particular target depth. Based on the physiologicalinformation, the system can automatically determine a target CPRcompression depth (e.g., calculate or look-up a new CPR compressiontarget depth) and, for example, provide feedback to a rescuer toincrease or decrease the depth/rate of the CPR compressions anddecompressions. Such feedback can include a sequence of desirablepositions to guide the rescuer to adjust his/her body position and/orbody motion to achieve a desirable combination of CPR compressions anddecompressions (e.g., depth, rate), rescuer fatigue, and/orphysiological outcome. Thus, the system can provide both feedbackrelated to how consistently a rescuer is administering CPR compressionsand decompressions at a target depth/rate, and feedback related towhether the target depth/rate can be adjusted based on measuredphysiological parameters, along with how the rescuer may enhance his/herbody positioning in administering CPR chest compression. If the rescuersdo not respond to such feedback and continues performed sub-optimal CPRchest compression, the system can then display an additional message toswitch out the person performing CPR chest compressions anddecompressions.

In some implementations, the system regularly monitors and adjusts thetarget CPR compression depth. In order to determine a desirable targetdepth, the system makes minor adjustments to the target CPR compressiondepth and observes how the change in compression depth affects theobserved physiological parameters before determining whether to makefurther adjustments to the target compression depth. More particularly,the system can determine an adjustment in the target compression depththat is a fraction of an inch or a centimeter and prompt the rescuer toincrease or decrease the compression depth by the determined amount. Forexample, the system can adjust the target compression depth by 2.5-10 mm(e.g., 2.5 mm to 5 mm or about 5 mm) and provide feedback to the rescuerabout the observed compression depth based on the adjusted targetcompression depth. Then, over a set period of time, the system canobserve the physiological parameters and, based on trends in thephysiological parameters without making further adjustments to thetarget compression depth and at the end of the set time period, candetermine whether to make further adjustments to the target compressiondepth.

And again, the actual performance of the rescuer against the revisedtarget can be continually monitored to determine when the rescuer'sperformance has fallen below an acceptable level, so that the rescuerand perhaps others can be notified to change who is performing the chestcompressions and decompressions. Also, each of the relevant parametersof patient condition discussed above with respect to the variousscreenshots can be made one of multiple inputs to a process fordetermining when rescuers who are performing one component of a rescuetechnique can be switched out with another rescuer, such as for reasonsof apparent fatigue on the part of the first rescuer.

While at least some of the embodiments described above describetechniques and displays used during manual human-delivered chestcompressions and decompressions, similar techniques and displays can beused with automated chest compression devices such as the AUTOPULSEdevice manufactured by ZOLL Medical, MA.

FIG. 12 shows an example flowchart 1200. At step 1202, a chestcompression monitor is attached to a patient's chest. The chestcompression monitor can be configured to display information that canassist with an ACD CPR treatment to be performed, as described withreference to FIGS. 3, 5, and 11 . At step 1204, an applicator body iscoupled with the chest compression monitor and at least one sensor isattached to the patient's chest. The sensor includes at least one of amotion sensor and a force sensor. The motion sensor can measure the atleast one parameter related to the ACD CPR treatment. The force sensorcan measure the at least one parameter related to the ACD CPR treatment.The motion sensor can measure the information for determining whether atleast one transition point of the ACD CPR treatment has been reached.The motion sensor can include one or more accelerometers configured todetect an acceleration signal associated with the displacement of the atleast the portion of the patient's chest. A first accelerometer can beconfigured to detect an acceleration signal associated with displacementof a first portion of the patient's chest and a second accelerometer canbe configured to detect an acceleration signal associated withdisplacement of a second portion of the patient's chest.

At step 1206, the ACD CPR treatment is initiated by executing anon-elevated compression treatment that starts from a neutral point ofthe patient's chest and continues until a transition point isidentified. The information for determining whether the at least onetransition point has been reached can include at least one ofdisplacement information and force information. At step 1208, feedbackis received real-time, such as from a storage device based on thedetected phase (e.g., non-elevated compression phase), as described withreference to FIG. 13 . The feedback can be phase specific. The feedbackcan assist with the phase specific (e.g., non-elevated compression)treatment, as described with reference to FIGS. 3, 5, and 11 . Forexample, the feedback signal can include providing a prompt to maintainat least one of a compression force, increase in compression depth and acompression rate according to the desired treatment protocol. The promptto maintain at least one of a compression force and a compression ratecan include at least one of an audio prompt, a verbal prompt, anon-verbal prompt, a visual prompt, a graphical prompt and a hapticprompt. The prompt to maintain at least one of a compression force and acompression rate can include a signal for operating an automatedcompressor. The feedback signal can include information regardingpatient's chest displacement below the neutral point (e.g., ribdisplacement below a breakage point) and a warning for the rescuer tolimit the compression force applied, so that excess force is not appliedto the ribs to prevent breakage of the patient's ribs. In someimplementations, the feedback associated with non-elevated compressionis stored to be accessible at a later time.

At 1210, a non-elevated compression is maintained. The hold time of themaintained non-elevated compression can be between about 20-100milliseconds, about 50-200 milliseconds, or about 10-1000 milliseconds.The hold time can be sufficient to promote net blood flow to the head ofthe patient. At step 1212, CPR feedback is received. The feedback signalcan include at least one of an audio prompt, a verbal prompt, anon-verbal prompt, a visual prompt, a graphical prompt and a hapticprompt indicating the timing, during which non-elevated compression ismaintained. In some implementations, the feedback associated withmaintained non-elevated compression is stored to be accessible at alater time.

At step 1214, a non-elevated decompression treatment is executed. Atstep 1216, CPR feedback is received. The feedback signal can includeproviding a prompt to apply a desired release velocity duringdecompression upstroke for providing a negative intrathoracic pressureaccording to the desired treatment protocol. The prompt to maintain thedesired release velocity can include at least one of an audio prompt, averbal prompt, a non-verbal prompt, a visual prompt, a graphical promptand a haptic prompt. The prompt to maintain the desired release velocitycan include a signal for operating an automated compressor. In someimplementations, the feedback associated with non-elevated decompressionis stored to be accessible at a later time.

At step 1218, an elevated decompression treatment is executed. At step1220, CPR feedback is received. The feedback signal can includeproviding a prompt to apply a sufficient release velocity duringdecompression upstroke for providing a negative intrathoracic pressureaccording to the desired treatment protocol. The at least one parameterrelated to the ACD CPR treatment can include at least one ofdisplacement, velocity, acceleration, time, work, power, pressure,direction and orientation. The parameter provided by the feedback signalcan be selected based on a comparison of one or more parameters withparticular ranges and thresholds. For example, each of the measuredparameters (displacement, velocity, acceleration, time, work, power,pressure, direction and orientation) can be compared to a correspondingpreset range or threshold and upon detection that a parameter is out ofrange a feedback signal is generated to provide an alert and guidancefor a corrective action (e.g., increase or decrease of a particularparameter). The feedback signal can include providing a prompt tomaintain the applicator device according to a desired orientation anddirection during application of the ACD CPR treatment to ensure optimalapplication of force while reducing risk of rib and/or skin injury. Thefeedback signal can include a prompt to increase at least one ofdisplacement, velocity, acceleration, power, pressure or force appliedto the patient's chest during decompression upstroke to reach a targetdecompression level within an optimal period of time (e.g., that enablesoptimal vascularization and oxygenation). The feedback signal caninclude a prompt to limit at least one of displacement, velocity,acceleration, power, pressure or force applied to the patient's chestduring decompression upstroke for reducing risk of rib and/or skininjury according to the desired treatment protocol. The prompt to limita force applied to the patient's chest during decompression upstroke caninclude at least one of an audio prompt, a verbal prompt, a non-verbalprompt, a visual prompt, a graphical prompt and a haptic prompt. Theprompt to limit a force applied to the patient's chest duringdecompression upstroke can include a signal for operating an automatedcompressor. The feedback signal can include providing a prompt toventilate during decompression upstroke. The prompt to ventilate caninclude at least one of an audio prompt, a verbal prompt, a non-verbalprompt, a visual prompt, a graphical prompt and a haptic prompt. Theprompt to ventilate can include a signal for operating an automatedventilator. In some implementations, the feedback associated withelevated decompression is stored to be accessible at a later time.

At step 1222, an elevated compression is maintained. The hold time ofthe maintained elevated compression can be between about 50-200milliseconds. The hold time can be sufficient to promote net blood flowto the heart of the patient. At step 1224, feedback is receivedindicating continuing ACD CPR chest compression treatment (returning tostep 1206) or interrupting ACD CPR chest compression treatment. In someimplementations, the feedback associated with maintained elevateddecompression is stored to be accessible at a later time.

Since the time intervals between the various phases e.g. 1206, 1210,1214, 1218, 1222 of the compression cycle can be closely-spaced in time,the rescuer delivering compressions will not be able to properly receivethe information and respond to the feedback and otherwise interactsubstantially instantaneously with the feedback, due to natural humandelay. The CPR feedback may be generated and received after thecompletion of two or more phases 102, 104, 106, 108 of the compressioncycle. The feedback may also be the aggregation, either statistically orother mathematical operation of two or more cycles of a measuredparameter of a particular phase, so as to sufficiently allow the rescuerto respond to the feedback in a timely manner. For instance, thestatistical operation might be mean, median, maximum, minimum, varianceof the associated feedback parameters. A mathematical operation might besum. The measured parameter might be maximum velocity, minimum velocity,maximum force, minimum force, distance, and/or other appropriatemeasure. The CPR feedback may be generated and received after thedetected conclusion of one or more chest compression cycles.

FIG. 13 shows a computer system 1300 that could be a component of, forexample, a defibrillator (e.g., the defibrillator 112 shown in FIG. 3 )or an ACD device (e.g., the ACD device 208 shown in FIG. 4 , orprocessor circuit 535 in FIG. 5B) or another kind of computer system(e.g., the computer system 110 shown in FIG. 3 ). The computer system1300 can be used, for example, for computing the quality of one or morecomponents of ACD CPR chest compression provided to a patient andgenerating feedback to rescuers, including feedback to change rescuerswho are performing some components of the CPR chest compression. Thesystem 1300 can be implemented in various forms of digital computers,including computerized defibrillators laptops, personal digitalassistants, tablets, and other appropriate computers. Additionally, thesystem can include portable storage media, such as, Universal Serial Bus(USB) flash drives. For example, the USB flash drives can storeoperating systems and other applications. The USB flash drives caninclude input/output components, such as a wireless transmitter or USBconnector that can be inserted into a USB port of another computingdevice.

The system 1300 includes a processor 1310, a memory 1320, a storagedevice 1330, and an input/output device 1340. Each of the components1310, 1320, 1330, and 1340 are interconnected using a system bus 1350.The processor 1310 is capable of processing instructions for executionwithin the system 1300. The processor can be designed using any of anumber of architectures. For example, the processor 1310 can be a CISC(Complex Instruction Set Computers) processor, a RISC (ReducedInstruction Set Computer) processor, or a MISC (Minimal Instruction SetComputer) processor.

In one implementation, the processor 1310 is a single-threadedprocessor. In another implementation, the processor 1310 is amulti-threaded processor. The processor 1310 is capable of processinginstructions stored in the memory 1320 or on the storage device 1330 todisplay graphical information for a user interface on the input/outputdevice 1340.

The memory 1320 stores information within the system 1300. In oneimplementation, the memory 1320 is a computer-readable medium. In oneimplementation, the memory 1320 is a volatile memory unit. In anotherimplementation, the memory 1320 is a non-volatile memory unit.

The storage device 1330 is capable of providing mass storage for thesystem 1300. In one implementation, the storage device 1330 is acomputer-readable medium. In various different implementations, thestorage device 1330 can be flash storage, a hard disk device, an opticaldisk device, or a tape device.

The input/output device 1340 provides input/output operations for thesystem 1300. In one implementation, the input/output device 1340includes a keyboard and/or pointing device. In another implementation,the input/output device 1340 includes a display unit for displayinggraphical user interfaces.

The features described can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The apparatus can be implemented in a computerprogram product tangibly embodied in an information carrier, e.g., in amachine-readable storage device for execution by a programmableprocessor; and method steps can be performed by a programmable processorexecuting a program of instructions to perform functions of thedescribed implementations by operating on input data and generatingoutput. The described features can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. A computer program is a set of instructions that can be used,directly or indirectly, in a computer to perform some activity or bringabout some result. A computer program can be written in any form ofprogramming language, including compiled or interpreted languages, andit can be deployed in any form, including as a stand-alone program or asa module, component, subroutine, or other unit suitable for use in acomputing environment.

Suitable processors for the execution of a program of instructionsinclude, by way of example, both general and special purposemicroprocessors, and the sole processor or one of multiple processors ofany kind of computer. Generally, a processor will receive instructionsand data from a read-only memory or a random access memory or both. Theessential elements of a computer are a processor for executinginstructions and one or more memories for storing instructions and data.Generally, a computer will also include, or be operatively coupled tocommunicate with, one or more mass storage devices for storing datafiles; such devices include magnetic disks, such as internal hard disksand removable disks; magneto-optical disks; and optical disks. Storagedevices suitable for tangibly embodying computer program instructionsand data include all forms of non-volatile memory, including by way ofexample semiconductor memory devices, such as EPROM, EEPROM, and flashmemory devices; magnetic disks such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,ASICs (application-specific integrated circuits).

To provide for interaction with a user, the features can be implementedon a computer having an LCD (liquid crystal display) or LED display fordisplaying information to the user and a keyboard and a pointing devicesuch as a mouse or a trackball by which the user can provide input tothe computer.

The features can be implemented in a computer system that includes aback-end component, such as a data server, or that includes a middlewarecomponent, such as an application server or an Internet server, or thatincludes a front-end component, such as a client computer having agraphical user interface or an Internet browser, or any combination ofthem. The components of the system can be connected by any form ormedium of digital data communication such as a communication network.Examples of communication networks include a local area network (“LAN”),a wide area network (“WAN”), peer-to-peer networks (having ad-hoc orstatic members), grid computing infrastructures, and the Internet.

The computer system can include clients and servers. A client and serverare generally remote from each other and typically interact through anetwork, such as the described one. The relationship of client andserver arises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

Many other implementations other than those described can be employed,and can be encompassed by the following claims.

1-75. (canceled)
 76. An apparatus for automatically providing an activecompression decompression (ACD) cardiopulmonary resuscitation (CPR)treatment to a patient in need of emergency assistance, the apparatuscomprising: at least one sensor configured to be coupled to thepatient's chest and to measure force applied during the ACD CPRtreatment to the patient's chest according to phases, the phasescomprising at least an elevated compression phase, a non-elevatedcompression phase, an elevated decompression phase, and a non-elevateddecompression phase; and one or more processors and a non-transitorycomputer readable storage medium encoded with a computer programcomprising instructions that, when executed, cause the one or moreprocessors to perform operations comprising: processing the measuredforce during the ACD CPR treatment, determining, based on the processedforce, whether at least one transition point between a current phase anda next phase in the ACD CPR treatment has been reached, and in responseto determining that the transition point between the current phase andthe next phase in the ACD CPR treatment has been reached, adjusting oneor more application parameters for the ACD CPR treatment.
 77. Theapparatus of claim 76, comprising a piston configured to apply the forceon the at least a portion of the patient's chest according to the one ormore application parameters.
 78. The apparatus of claim 77, wherein theat least one sensor is included at a distal end of the piston.
 79. Theapparatus of claim 76, wherein the at least one sensor comprises a forcesensor or a pressure sensor.
 80. The apparatus of claim 76, whereinprocessing the force during the ACD CPR treatment comprises determininga force amplitude, an impulse, a distance, an average force, or a peakforce.
 81. The apparatus of claim 76, wherein processing the forceduring the ACD CPR treatment comprises comparing the force to athreshold.
 82. The apparatus of claim 76, wherein processing the forceduring the ACD CPR treatment comprises determining a compliance of thepatient's chest wall.
 83. The apparatus of claim 76, wherein adjustingthe one or more application parameters for the ACD CPR treatment tocorrespond to the subsequent phase of the ACD CPR treatment comprises agradual variation of the force and a hold time with the force at aconstant level.
 84. The apparatus of claim 76, wherein the one or moreapplication parameters comprise a release velocity during decompressionupstroke for providing a negative intrathoracic pressure according to atreatment protocol.
 85. The apparatus of claim 76, wherein the one ormore application parameters comprise the force to be applied to thepatient's chest during decompression upstroke according to a desiredtreatment protocol.
 86. The apparatus of claim 76, wherein the one ormore application parameters comprise at least one of displacement,velocity, acceleration, time, work, power, pressure, direction, andorientation.
 87. The apparatus of claim 76, wherein the one or moreapplication parameters comprise a distance above a neutral point and adepth of compression below the neutral point.
 88. The apparatus of claim87, wherein the at least one transition point is at least one of betweenan elevated compression phase and a non-elevated compression phase,between the elevated decompression phase and the elevated compressionphase, between the elevated decompression phase and a hold time abovethe neutral point, and between a hold time above the neutral point andthe elevated compression phase.
 89. The apparatus of claim 88, whereinthe hold time is between about 50-200 milliseconds.
 90. The apparatus ofclaim 87, wherein the at least one transition point is at least one ofbetween the non-elevated compression phase and the non-elevateddecompression phase, between the non-elevated compression phase and ahold time below the neutral point, and between hold time below theneutral point and the non-elevated decompression phase.
 91. Theapparatus of claim 90, wherein the hold time is between about 50-200milliseconds.
 92. The apparatus of claim 76, wherein the at least onetransition point is between the non-elevated decompression phase and theelevated decompression phase.
 93. The apparatus of claim 76, wherein theat least one transition point between the current phase and the nextphase in the ACD CPR treatment comprises zero static compression forceand zero static decompression force being exerted on to the patient'schest during the ACD CPR treatment.
 94. The apparatus of claim 76,comprising a user interface configured to display the one or moreapplication parameters during the ACD CPR treatment.
 95. The apparatusof claim 94, wherein the user interface is configured for displaying atleast one of information representing effectiveness of CPR and anindication of a phase of the ACD CPR treatment.
 96. The apparatus ofclaim 95, wherein the user interface is configured to be displayed on adevice external to the apparatus comprising at least one of asmartphone, a smartwatch, a tablet device, a monitor, a diagnosticdevice, and a defibrillator.
 97. The apparatus of claim 76, comprisingan adhesive pad configured to be adhered to at least a portion of apatient's chest.
 98. The apparatus of claim 97, wherein the adhesive padcomprises pressure-sensitive adhesives comprising medical bandageadhesives, transdermal patches.
 99. The apparatus of claim 97, whereinthe adhesive pad is configured to transfer a decompression force betweenthe apparatus and the patient's chest during the ACD CPR treatmentwithout detaching.
 100. The apparatus of claim 76, comprising a portabledevice.
 101. The apparatus of claim 76, wherein determining whether theat least one transition point has been reached comprises: identifying aneutral point associated with a zero force being exerted on thepatient's chest during a cycle of the ACD CPR treatment, wherein theneutral point changes over a course of the ACD CPR treatment, anddetermining, based on the neutral point, whether the at least onetransition point between the current phase and the next phase in the ACDCPR treatment has been reached.
 102. The apparatus of claim 76, whereinthe one or more application parameters for the ACD CPR treatment areadjusted to correspond to a subsequent phase of the ACD CPR treatment.